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Mesenchymal chondrosarcoma (MC) is a rare cartilaginous tumour that occurs in the extraskeletal locations in about one-third of cases. It is aggressive in behaviour and may involve the lower extremities, central nervous system or spine. Mesenchymal tumours are known for distant metastasis; however, metastasis to bilateral kidneys after treatment has not been reported earlier. We present a case of a soft-tissue intramuscular MC of the thigh in a 38-year-old patient which had been surgically excised after neoadjuvant chemotherapy. The patient presented with bilateral dense calcified renal masses after 6 years, which were cytologically proven as MC metastases. In the evaluation of bilateral calcified renal masses in patients with a history of MC, metastasis should be considered.

Tumor-induced osteomalacia is a rare and often misdiagnosed condition that presents with progressively worsening unexplained chronic pain and proximal muscle weakness. The osteomalacia leads to multiple stress fractures which do not heal properly, leading to progressive disability. It is caused by chronic hypophosphatemia due to inappropriate urinary phosphate wasting. This is due to a typically benign mesenchymal tumor that over-secretes a phospaturic hormone. Neurologists need to appreciate the relevance of chronic hypophosphatemia in people with chronic unexplained pain, as timely diagnosis and treatment of tumour-induced osteomalacia can be curative.

Tumor-induced osteomalacia (TIO) is an acquired fibroblast growth factor 23 (FGF23)-related hypophosphatemic osteomalacia caused by phosphaturic mesenchymal tumors (PMTs) developed in the bone or soft tissue. Diagnostic delay should be addressed, and ideal techniques to localize PMTs and efficient treatment options should be explored to improve the outcomes of this rare disease. To clarify the detailed clinical course and outcomes of TIO patients, retrospective questionnaire surveys were conducted among physicians from the Japanese Society for Bone and Mineral Research (JSBMR) and the Japan Endocrine Society (JES). The primary survey collected the number of TIO patients between January 2007 and December 2018. The secondary survey aimed to obtain the detailed characteristics, laboratory data, and outcomes. Eighty-eight patients (52 males, mean: 52 years old) were included, and 24 patients were clinically diagnosed with TIO without localized PMTs. The median duration from the onset to detection of high FGF23 levels was 3.4 years, with 77 patients being initially misdiagnosed. Among the methods used to detect small, localized PMTs (≤10 mm), fluorine-18-fluorodeoxyglucose-positron emission tomography/computed tomography and somatostatin receptor scintigraphy were less sensitive than somatostatin receptor positron emission tomography/computed tomography (SRPET/CT). Systemic venous sampling (SVS) of FGF23 was performed in 53 patients; among them, SVS was considered useful for detecting localized PMTs in 45 patients with diverse tumor sizes. Finally, 45 patients achieved biochemical remission by surgery, 39 patients continued pharmaceutical treatment, including burosumab (11 patients), and four patients died. These results encouraged us to further increase the awareness of TIO and to improve the accessibility of SRPET/CT and SVS. Further evidence about the efficacy of new pharmaceutical treatments is awaited. © 2022 American Society for Bone and Mineral Research (ASBMR).

This study reviews publications to describe the signs, symptoms and impact of tumour-induced osteomalacia (TIO) on patients' burden of disease. TIO is associated with a spectrum of signs and symptoms imposing a significant clinical burden, but the psychosocial impact of this rare disease has been poorly researched so far.To describe the signs, symptoms and impacts of tumour-induced osteomalacia (TIO) and summarise the state of research on the burden of disease of this ultra-rare condition.A targeted literature review was conducted in PubMed using pre-defined search terms. Relevant articles published between 1980 and 2021 were screened for inclusion. Seventy records were selected for analysis. Data were extracted and grouped into categories and sub-categories to identify recurrent signs, symptoms and impacts of TIO and describe the burden on patients. Chord diagrams were created to analyse the relationships between different TIO outcomes and characterise the presentation of TIO.Although the number of articles on TIO published have been increasing over the past 20 years, most studies were case reports and case series (n = 65/70) and only few were studies with higher quality of evidence (n = 5/70). Most articles were based on data reported by clinicians (n = 67/70). Patients with TIO experienced a combination of outcomes including chronic pain, weakness, skeletal-related manifestations and limitations in mobility. Only a few studies (n = 2/70) analysed the burden of TIO on the emotional wellbeing and on the work life of the patient.Patients with TIO present with a spectrum of signs and symptoms that impose a significant burden. The impact on the psychosocial wellbeing of patients should be further investigated, as this has been poorly researched so far. Studies with high quality of evidence should be designed to further the understanding of the burden of disease of TIO from the patient's perspective.

Pseudotumors of the sternoclavicular joint are rare, poorly characterized pseudoneoplastic lesions previously reported in association with prior neck dissection and thought to result from mechanical instability of the muscles of the shoulder girdle. We report 25 examples of this distinctive process, occurring in patients without a history of neck dissection, typically sent in consultation out of concern for a primary bone or soft-tissue tumor. Cases occurred in 14 women and 11 men (median = 68 years of age) and involved the sternoclavicular joint (17 cases), sternomanubrial joint (2 cases) or other nearby locations (6 cases). The masses ranged from 0.4 to 6.4 cm in size (median = 2.2 cm). Twenty-one patients (84%) had a clinical history of osteoarthritis involving other joints. Clinical follow-up (16 patients; mean = 11.4 months; range = 2-40 months) was uniformly benign, without evidence of recurrent disease. Radiologic review showed changes of osteoarthritis, often with cystic change. Pathologic features included degenerating cartilage, fibrinoid debris, pseudocyst formation, and florid proliferation of myofibroblasts and capillaries. The differential diagnosis of sternoclavicular/sternomanubrial pseudotumors centers around cartilaginous tumors of bone, in particular chondrosarcoma. Careful clinical, radiographic, and pathologic correlations are essential in arriving at the correct diagnosis and avoiding overtreatment.

Background Phosphaturic mesenchymal tumors primarily cause tumor-induced osteomalacia, a rare paraneoplastic syndrome, and half occur in soft tissues. There are few reports about the surgical margins of these tumors. This study aimed to clarify the optimal surgical margin for phosphaturic mesenchymal tumors by analyzing radiological and histopathological features. Methods This study included eight cases, seven primary and one recurrent, of tumor-induced osteomalacia caused by soft-tissue phosphaturic mesenchymal tumors that were surgically treated between January 2000 and January 2019. We evaluated the radiological and histopathological features of all tumors and investigated the correlation of these features, the surgical margin, and recurrence of hypophosphatemia. Results The tumors were located in superficial (n = 5) and deep (n = 3) tissues. Six of the eight tumors had a clear boundary, but five had an irregular margin. Three tumors had a hypointense rim on T2-weighted images, indicating fibrous tumor encapsulation. Histopathological analysis revealed infiltrative growth in six of the eight tumors, which correlated with an irregular margin seen on imaging. Although there was no recurrence in patients treated with an intended wide margin >1 cm, one of the three patients treated with marginal tumor resection experienced a recurrence of hypophosphatemia, with histopathological analysis showing infiltration of subcutaneous fat. In contrast, two tumors with clear boundaries, regular margins, and fibrous capsule seen on imaging, had no infiltrative growth and were cured by marginal resection. In one recurrent case, tumor infiltration was observed in the previous surgical scar, which was not detected on preoperative imaging. Conclusions Soft-tissue phosphaturic mesenchymal tumors with an irregular boundary seen on imaging tend to be infiltrative, especially into subcutaneous fat, and should be treated by at least a 1-cm wide margin resection. Tumors with a fibrous capsule with clear and regular margins are cured by marginal margin resection. These findings could inform surgeons' decisions regarding the resection of soft-tissue phosphaturic mesenchymal tumors.

Bone and soft tissue sarcomas consist of a heterogeneous group of malignant tumors of mesenchymal origin that can affect patients from any age. The precise staging of these lesions determines the best therapeutic strategies and prognosis estimates. Two staging systems are the most frequently used: the system proposed by the University of Florida group, led by Dr. William F. Enneking (1980) and adopted by the Musculoskeletal Tumor Society (MSTS), and the system developed by the American Joint Committee on Cancer (AJCC) (1977), currently in its 8th edition (2017). This paper updates the reader on the staging of bone and soft tissue sarcomas affecting the musculoskeletal system. Resumo Os sarcomas ósseos e das partes moles consistem em grupo heterogêneo de neoplasias malignas de origem mesenquimal que podem ocorrer em qualquer faixa etária. O estadiamento preciso destas lesões determina as melhores estratégias terapêuticas e estimativas de prognóstico. Dois sistemas de estadiamento são os mais frequentemente empregados no manejo destas neoplasias: o sistema proposto pelo grupo da Universidade da Flórida, liderado pelo Dr. William F. Enneking (1980), adotado pela Musculoskeletal Tumor Society (MSTS) e o sistema desenvolvido pela American Joint Committee on Cancer (AJCC) (1977) que se encontra em sua 8a edição (2017). O presente artigo busca atualizar o leitor a respeito do estadiamento dos sarcomas ósseos e das partes moles que acometem o sistema musculoesquelético.

The co-incidence of systemic lupus erythematosus (SLE) and tuberous sclerosis with pulmonary lymphangioleiomyomatosis (LAM) and renal angiomyolipoma (AML) is rare. In such patients, the rupture of renal AML may result in fatal circumstances, but this may be preventable.A 22-year-old Asian woman with SLE was admitted to our hospital with severe left-flank pain. Imaging studies showed the bilateral rupture of multiple renal AMLs.The patient underwent emergency selective transcatheter embolization (TE) of the left renal artery. After TE and massive hydration, the patient complained of dyspnea and postembolization syndrome with fever. The chest computed tomography (CT) revealed pulmonary LAM, pulmonary edema with bilateral pleural effusions, and pneumonic consolidation. After the emergency procedure, the patient was treated with intravenous administration of antibiotics, diuretics, and nonsteroidal anti-inflammatory drugs for 10 days. The patient recovered favorably and was discharged 20 days after the treatment. She was diagnosed with renal AML and pulmonary LAM along with facial angiofibromas as well as tuberous sclerosis complex (TSC), although she had no TSC1 or TSC2 gene mutations.Although rare, SLE may coexist with TSC, along with LAM and AML, with a risk of AML rupture. The activation of the mTOR signaling pathway is shared between SLE and TSC. Thus, in patients with SLE, clinicians should consider imaging studies, such as kidney sonography and chest CT, to screen for possible manifestation of AML and LAM.

Background When assessing sharply delineated bone lesions of the mandibular angle on X-rays, numerous diagnoses must be considered. The static bone cavity (Stafne's bone cavity, SBC) is a harmless lingual bone depression of the mandibular angle that usually does not require any treatment. It is essential to differentiate this bone deformity from other lesions that may require treatment. Case report The 22-year-old patient was referred for further diagnosis and therapy after osteolysis of the mandible was noticed on a panoramic view (PV). The location and size of the lesion was typical of SBC. Only the three-dimensional representation of the lesion on cone beam computed tomographs revealed an intraosseous lesion. Histological examination of the lesion provided evidence of a fibrous neoplasm. Conclusion The typical image of SBC is ambiguous on plain radiographs such as PV. The radiological diagnosis of the lesion should be based on the representation of the region of interest in different planes.

Translocations involving FN1 have been described in a variety of neoplasms that share the presence of a cartilage matrix and may also contain a variable extent of calcification. Fusions of FN1 to FGFR1 or FGFR2 have been reported in nine soft tissue chondromas, mostly demonstrated indirectly by FISH analysis. Delineation of FN1 fusions with various partner genes will facilitate our understanding of the pathogenesis and diagnostic classification of these neoplasms. In this study, we present molecular, clinical, and pathologic features of 12 cartilaginous soft tissue neoplasms showing a predilection for the TMJ region and the distal extremities. We analyzed for gene fusions with precise breakpoints using targeted RNA-seq with a 115-gene panel. We detected gene fusions in ten cases, including three novel fusions, FN1-MERTK, FN1-NTRK1, and FN1-TEK, each in one case, recurrent FN1-FGFR2 fusion in five cases, FN1-FGFR1 in one case, and FGFR1-PLAG1 in one case. The breakpoints in the 5' partner gene FN1 ranged from exons 11-48, retaining the domains of a signal peptide, FN1, FN2, and/or FN3, while the 3' partner genes retained the transmembrane domain, tyrosine kinase (TK) domains, and/or Ig domain. The tumors are generally characterized by nodular/lobular growth of polygonal to stellate cells within a chondroid matrix, often accompanied by various patterns of calcification, resembling those described for the chondroblastoma-like variant of soft tissue chondroma. Additional histologic findings include extensive calcium pyrophosphate dihydrate deposition in two cases and features resembling tenosynovial giant cell tumor (TGCT). Overall, while the tumors from our series show significant morphologic overlap with chondroblastoma-like soft tissue chondroma, we describe findings that expand the morphologic spectrum of these neoplasms and therefore refer to them as "calcified chondroid mesenchymal neoplasms." These neoplasms represent a spectrum of chondroid/cartilage matrix-forming tumors harboring FN1-receptor TK fusions that include those classified as soft tissue chondroma as well as chondroid TGCT.

Objective. Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome characterized by chronic hypophosphatemia and osteomalacia. We present case of a patient with a protracted clinical course of TIO. TIO profoundly affected every aspect of his life with subsequent profound physical and psychosocial disabilities. Method. The review of a complex clinical presentation, serial laboratory investigations, and imaging modalities of a patient with TIO caused by a mesenchymal tumor. Results. The patient presented with chronic lower back pain, severe bilateral leg weakness, and multiple pathological fractures due to severe osteoporosis. His investigations revealed hypophosphatemia, low 1,25 dihydroxyvitamin D, phosphaturia and normal serum calcium, and parathyroid hormone. Elevated fibroblast growth factor 23 (FGF23) confirmed the diagnosis of TIO and 68Ga-DOTATATE-positron emission tomography/computed tomography (PET/CT) imaging correctly identified a tumor in the left femoral head. His clinical features and biochemical abnormalities promptly recovered after successful surgical resection of the mesenchymal tumor. Conclusion. The present case demonstrated the need to extensively investigate causes of generalized bone pain in patients with hypophosphatemia, as TIO is highly curable. Importantly, 68Ga-DOTATATE PET/CT imaging successfully identified the FGF23 producing tumor, which was undetectable by conventional imaging, favoring its early use in suspected TIO presentation. The present report highlights the importance of timely diagnosis of this complex medical condition, aiming to improve general awareness and enable better clinical outcomes for this rare disorder.

The experience with uterine inflammatory myofibroblastic neoplasms with an unfavorable outcome is limited. We present the clinicopathologic features of 9 such cases, including 8 inflammatory myofibroblastic tumors (IMTs) and 1 epithelioid inflammatory myofibroblastic sarcoma (EIMS). Median patient age for the IMT group was 50.5 years; the patient with EIMS was 43 years old. Patients presented with abnormal uterine bleeding, presumed fibroids, pelvic pain, arthralgia and low-grade fever, as well as an incidental finding. Median tumor size for the IMTs was 8.5 cm. The borders were either infiltrative or well-circumscribed. Histologically, IMTs were purely fascicular or myxoid or showed predominance of one or the other pattern. Seven tumors were spindled, and 1 was both spindled and epithelioid. Tumors had variable nuclear atypia, ranging from grade 1 to 3. All tumors had an inflammatory infiltrate-predominantly lymphocytic, majority had necrosis (62.5%) and none had lymphovascular invasion. 7/8 (87.5%) tumors were positive for ALK-1 by immunohistochemistry (IHC). One tumor was negative for ALK-1 by IHC but was positive for ALK fusion by fluorescence in situ hybridization and had TNS1-ALK fusion by next-generation sequencing (NGS). Three other tumors with NGS testing showed one of the following ALK-fusion partners: FN1, DCTN1, and IGFBP5. The EIMS had infiltrative borders, myxoid and hyalinized patterns, epithelioid cells, and no lymphovascular invasion. This tumor was ALK-1 positive by IHC, had ALK rearrangement by fluorescence in situ hybridization and RANBP2-ALK fusion by NGS. Extrauterine disease at time of diagnosis was noted in 2/8 (25%) of IMTs, and in the single case of EIMS. Seven patients had surgery as primary treatment, 1 patient had neoadjuvant chemotherapy and 1 patient declined treatment. Patients with recurrence were treated with a combination of chemotherapy, targeted therapy, radiotherapy or hormonal therapy. Most patients (71.4%) recurred within 24 months (mos). Two thirds of patients were alive with disease at last follow up (mean 43.6 mos). The patient with EIMS was alive with disease at 22 mos. IMT referral cases were initially diagnosed as smooth muscle tumors in 87.5% of cases; while the EIMS was diagnosed as high-grade endometrial stromal sarcoma. Lack of consideration of IMT in the differential diagnosis of smooth muscle tumors with myxoid features can result in misdiagnosis and under-utilization of targeted therapy in these patients.

Sarcoma and locally aggressive connective tissue tumors are a complex group of diseases with a growing number of histotypes in the most recent WHO classification. Most of these tumors are rare (incidence6/10

Phosphaturic mesenchymal tumors (PMTs) are neoplasms associated with tumor-induced osteomalacia. Patients typically present with pathologic fractures in the setting of chronic hypophosphatemic hyperphosphaturic osteomalacia, as well as gradual muscle weakness, bone pain, and difficulty walking. Because of their rarity and nonspecific symptomatology, phosphaturic mesenchymal tumors often go undiagnosed for years. Even when discovered on imaging, the tumors can be diagnostically challenging for radiologists. Phosphaturic mesenchymal tumors often tend to be small and can be located nearly anywhere in the body, and, therefore, can mimic many other tumors. This case highlights the imaging and pathologic markers of a phosphaturic mesenchymal tumor, often found in a patient with tumor-induced osteomalacia.

Tumor induced osteomalacia is a rare acquired disease. The cause is a mesenchymal tumor secreting fibroblast growth factor 23 (FGF23). An excessive amount of FGF 23 disrupts the metabolism of phosphorus and vitamin D, which leads to severe paraneoplastic syndrome, manifested in the form of multiple fractures, severe pain in the bones and generalized myopathy. With oncogenic osteomalacia, a complete cure is possible with radical resection of the tumor. Unfortunately, localization, small size of formations and rare frequency of occurrence lead to the fact that the disease remains unrecognized for a long time and leads to severe, disabling consequences. A step-by-step approach to diagnosis improves treatment outcomes. First, a thorough anamnesis is collected, then functional visualization is performed and the diagnosis is confirmed by anatomical visualization of the tumor. After that, the method of choice is a surgical treatment. If resection is not possible, then conservative therapy with active metabolites of vitamin D and phosphorus salts is indicated. New therapeutic approaches, such as the antibody to FGF23 or the pan-inhibitor of receptors to FGF, are actively developing. This article provides an overview of modern approaches to the diagnosis and treatment of this disease.

Background Fibrous hamartoma of infancy (FHI) is a rare soft tissue lesion arising as a subcutaneous mass involving the axilla, trunk, and upper arm in infants and children

METHODS Seventy-six patients who had surgically removed tumors that caused osteomalacia were included in this retrospective investigation. All patients underwent both 18F-FDG and 68Ga-DOTATATE PET/CT prior to surgery. The prognostic value of presurgical FDG PET/CT study was determined with 5-year follow-up. RESULTS In the presurgical evaluation, 68Ga-DOTATATE detected lesions in all 76 patients. However, FDG PET/CT was positive in only 25 among all 76 patients. Following surgical removal of the causative tumor, all 76 patients had symptomatic relief and normalization of the serum phosphate level initially. However, 15 of 76 cases (19.7%) had recurrent hypophosphatemia and became symptomatic again during the follow-up. Among these 15 patients with recurrence, 11 (73.3%) had recurrent lesions at the original location of the resected causative tumors, whereas 4 were in other locations due to malignant nature of the primary tumor. Interestingly, 14 of these 15 patients with recurrent disease had positive presurgical FDG PET/CT findings with an incident ratio of 56.0% (14 of 25). In contrast, only 1 patient with recurrent disease had negative presurgical FDG PET/CT scan with an incident ratio of 1.9% (1 of 51), significantly less than the positive presurgical FDG PET/CT group (P < 0.05). CONCLUSIONS A positive presurgical FDG PET/CT suggests increased likelihood for possible recurrence of TIO after surgical resection. In contrast, when a causative tumor detected by 68Ga-DOTATATE PET/CT does not have elevated activity on FDG PET/CT, the chance of recurrence is very small.

Background Mandible can be the site of benign or malignant lesions of different origins, including odontogenic and non-odontogenic lesions. Cartilage-forming tumors have been rarely reported at this site. Chondrosarcoma is a rare malignant cartilage-producing neoplasm that is extremely rare in the mandible. The rarity of cartilage-forming tumor occurrence in the mandible can make diagnosis difficult for pathologists, as they do not expect this type of tumor at this anatomical site. Here we report a case of chondrosarcoma of mandibular angle. Case presentation A 70-year-old Moroccan male patient consulted a dentist for wisdom tooth pain. Wisdom tooth extraction was conducted. After 6 months, the patient reported the recurrence of pain associated with swelling in the mandibular area and paresthesia along the path of the mandibular nerve. A panoramic radiograph demonstrated a mixed radiolucent–opaque lesion involving the mandibular angle. Computed tomography showed a large osteolytic spontaneously hypointense and multilobulated lesion. A biopsy was done. Histopathological examination revealed sheets and irregular lobules of atypical cells presenting cartilaginous differentiation. Tumor cells showed severe nuclear atypia and were located within a hyaline cartilage matrix. Some foci of necrosis were noted. Osteoid deposits were not found. The patient was diagnosed with grade III chondrosarcoma and underwent a right segmental mandibulectomy with submandibular lymph node dissection. Macroscopically, the tumor was localized in the mandibular angle with extension in the mandibular body. Histopathology confirmed the previous diagnosis of grade III chondrosarcoma and did not show any lymph node metastasis. Conclusions Owing to many histological similarities, grade III chondrosarcoma must be distinguished from chondroblastic osteosarcoma and metastatic lesions. In addition, chondroblastic osteosarcoma of the jawbones has a worse prognosis than chondrosarcoma, making the distinction between these two malignant tumors the most important concern of the pathologist when dealing with a cartilage-forming tumor at this site. Surgery with wide excision margins remains the best therapeutic approach, while the role of radiotherapy is controversial. The management of mandibular chondrosarcoma requires a multidisciplinary approach involving maxillofacial surgeons, radiologists, pathologists, and oncologists.

68Ga-FAPI is a newly developed tumor imaging agent with promising clinical applications. However, benign lesions may also show increased FAPI activity. We accidentally discovered that Schmorl node expressed FAPI activity in a patient with sweat gland cancer. Thus, greater awareness is needed that Schmorl nodes are a potential reason for false-positive uptake on 68Ga-FAPI PET/CT.

Phosphaturic mesenchymal tumour (PMT) is a rare tumour that occurs in bone or soft tissue and is associated with production of fibroblast growth factor 23 (FGF23) leading to tumor-induced osteomalacia. We report three cases of PMT involving the head and neck that highlight the broad spectrum of clinical and histologic features of PMT. One of these lesions from the hard palate demonstrated an admixture of epithelial and mesenchymal elements, a feature that can pose a diagnostic challenge. The diagnostic utility of immunohistochemistry including FGF23, somatostatin receptor 2A, SATB2, ERG and CD56 is discussed. The biochemical pathway in the development of PMT associated tumor induced osteomalacia and its role in investigations and management of PMT is also described.

External auditory canal cancer is a rare disease which can be treated by surgery or chemoradiation. The most common histological type is squamous cell carcinoma, but rare types such as adenocarcinoma have been reported and are thought to be derived from the ceruminous glands. Here, we present a case of ceruminous adenocarcinoma, not otherwise specified (NOS) in the external auditory canal. A 72-year-old woman was referred to our department with discomfort due to a mass in the external ear canal. No typical symptoms of malignancy, such as pain or bleeding, were noted at the initial examination. The patient underwent a total excision under local anesthesia as a diagnostic treatment. She was diagnosed with ceruminous adenocarcinoma, NOS based on the results of immunostaining of the excised specimen, and is currently being followed up as an outpatient. Adenocarcinoma is thought to originate from the cerumen glands of the ear canal and the lack of specific symptoms may make it difficult to differentiate it from benign tumors. Although adenocarcinoma, NOS has been reported in the head and neck region, there have been no reported cases occurring in the external ear canal, and to the best of our knowledge, this is the first report.

International audience; Acral soft tissue tumors are common neoplasms, a subset of which pose a diagnostic challenge. We report 10 cases of a previously unrecognized acral benign soft tissue tumor. These tumors arose on the fingers and toes and involved bone in half of cases. Histologically, the tumors were lobulated and displayed an abundant stroma made of variable fibrous, chondroid and myxoid material reminiscent of cartilaginous or myoepithelial differentiation. Tumor cells harbored small round to reniform nuclei with clear chromatin and inconspicuous nucleoli along with scant eosinophilic cytoplasm. The cells were mostly arranged haphazardly in the stroma but also in small clusters. No mitotic activity was detected. No specific feature was identified in recurrent cases. By immunohistochemistry, the cells consistently stained for CD34 (10/10), ERG (9/10), and SOX9 (7/10). Whole RNA sequencing identified a previously undescribed recurrent in frame THBS1-ADGRF5 gene fusion in all cases. The transcript was confirmed by RT-PCR and was not found in the control group of mimickers including soft tissue chondromas. We propose the name of Acral FibroChondroMyxoid Tumors for this new entity.

The tumor microenvironment (TME) is a complex meshwork of extracellular matrix (ECM) macromolecules filled with a collection of cells including cancer-associated fibroblasts (CAFs), blood vessel associated smooth muscle cells, pericytes, endothelial cells, mesenchymal stem cells and a variety of immune cells. In tumors the homeostasis governing ECM synthesis and turnover is disturbed resulting in abnormal blood vessel formation and excessive fibrillar collagen accumulations of varying stiffness and organization. The disturbed ECM homeostasis opens up for new types of paracrine, cell-cell and cell-ECM interactions with large consequences for tumor growth, angiogenesis, metastasis, immune suppression and resistance to treatments. As a main producer of ECM and paracrine signals the CAF is a central cell type in these events. Whereas the paracrine signaling has been extensively studied in the context of tumor-stroma interactions, the nature of the numerous integrin-mediated cell-ECM interactions occurring in the TME remains understudied. In this review we will discuss and dissect the role of known and potential CAF interactions in the TME, during both tumorigenesis and chemoresistance-induced events, with a special focus on the "interaction landscape" in desmoplastic breast, lung and pancreatic cancers. As an example of the multifaceted mode of action of the stromal collagen receptor integrin α11β1, we will summarize our current understanding on the role of this CAF-expressed integrin in these three tumor types., info:eu-repo/semantics/published

To describe our clinical experience with surgical treatments for sinonasal phosphaturic mesenchymal tumors diagnosed at our institution.Retrospective case series.Affiliated Sixth People's Hospital, Shanghai Jiao Tong University.We retrospectively reviewed the medical records of 10 patients diagnosed with phosphaturic mesenchymal tumors associated with tumor-induced osteomalacia between December 2014 and October 2019.There were 4 men and 6 women with a disease course of 1 to 19 years. All patients exhibited hypophosphatemia and tumor-induced osteomalacia. The tumor was located in the sinonasal region, frontal bone, and temporal bone in 8 patients, 1 patient, and 1 patient, respectively. Technetium-99m octreotide scintigraphy was used for tumor localization in 4 cases. Six patients underwent endoscopic resection; the remaining 4 underwent unilateral transorbital anterior and posterior ethmoid artery ligation + endoscopic resection, endoscopic resection + skull base repair, internal carotid artery stenting + transcatheter arterial embolization + temporal bone tumor excision + adipose tissue plugging, and endoscopic resection + transfrontal craniotomy (n = 1 each). Two patients had a history of incomplete endoscopic resection. All patients achieved clinical remission and normalized biochemical indices after surgery. Only 1 patient developed recurrence and died of a brain hernia.A diagnosis of sinonasal phosphaturic mesenchymal tumors should be based on a combination of clinical, imaging, and pathological findings. Technetium-99m octreotide scintigraphy helps in locating the tumor. Complete surgical excision guarantees clinical remission, and preoperative transcatheter arterial embolization or feeding artery ligation may reduce intraoperative bleeding in cases of highly vascularized tumors.

Background Tumor-induced osteomalacia is a rare, acquired paraneoplastic syndrome, including hypophosphatemia, high serum alkaline phosphatase, reduced active vitamin D, suboptimal bone mineral density, bone pain, fragility fractures, and muscle weakness. Case presentation We report a case of 74–year–old male of mixed ancestry with hypophosphatemia resistant to treatment despite optimal compliance, associated with profound reduction of bone mineral density and multiple nontraumatic fractures, including bilateral rib fractures, lower-thoracic (T11, T12) vertebrae, and two fractures involving the surgical and anatomical neck of the right humerus. We discuss an approach to identifying the underlying cause of hypophosphatemia associated with fragility fractures, and options for management of this rare condition. Conclusion Although rare, tumor-induced osteomalacia can be diagnosed if a logical stepwise approach is implemented. Surgery could be curative if the tumor is properly located and is resectable.

Effective treatment of advanced invasive cervical cancer remains challenging nowadays. Herein, single-nucleus RNA sequencing (snRNA-seq) and SpaTial Enhanced REsolution Omics-sequencing (Stereo-seq) technology are used to investigate the immunological microenvironment of cervical squamous cell carcinoma (CSCC), a major type of cervical cancers. The expression levels of most immune checkpoint genes in tumor and inflammation areas of CSCC were not significantly higher than those in the non-cancer samples except for LGALS9 and IDO1. Stronger signals of CD56+ NK cells and immature dendritic cells are found in the hypermetabolic tumor areas, while more eosinophils, immature B cells, and Treg cells are found in the hypometabolic tumor areas. Moreover, a cluster of cancer-associated fibroblasts (CAFs) are identified around some tumors, which highly expressed ACTA2, POSTN, ITGB4, and FAP. The CAFs might support the growth and metastasis of tumors by inhibiting lymphocyte infiltration and remodeling the tumor extracellular matrix. Furthermore, CAFs are associated with poorer survival probability in CSCC patients and might be present in a small fraction (∼20%) of advanced cancer patients. Collectively, these findings might enhance understanding of the CSCC immunological microenvironment and shed some light on the treatment of advanced CSCC.

AIM To validate an imaging protocol for the management of solitary central cartilage tumours (CCTs) of the proximal humerus and around the knee. MATERIALS AND METHODS Over a 10-year period, 387 patients were identified with a CCT in the proximal humerus, distal femur, and proximal tibia, who were referred to a single unit either from primary/secondary care or tertiary care directly to Royal Orthopaedic Hospital, a specialist orthopaedic oncology service. The initial magnetic resonance imaging (MRI) images and any follow-up images were evaluated for length of tumour, presence/absence of endosteal scalloping, or aggressive/malignant features. The cases were categorised into one of seven types according to the Birmingham Atypical Cartilage Tumour Imaging Protocol (BACTIP). The outcome in the cases was assessed to ascertain if application of the protocol would have led to any delay in the diagnosis of malignant transformation to a chondrosarcoma. RESULTS The incidence of malignancy (chondrosarcoma) increased with ascending BACTIP. There was a 100% benign diagnosis (enchondroma) in types IA and IB, 96% in IIA, and 83% in IIB. Fifty-seven percent of type IIC and 97% type III were diagnosed as malignant. In only one case would the application of the protocol have led to a 5-month delay in the diagnosis of chondrosarcoma. CONCLUSIONS This retrospective study confirms the BACTIP as a useful tool for the general radiologist in the initial assessment of CCT in the proximal humerus and around the knee with the exception of the proximal fibula. In particular, determining which cases need prompt referral to a specialist orthopaedic oncology service for further assessment.

A chondroma is a common benign cartilaginous tumor. However, a primary soft tissue chondroma of the posterior mediastinum is very rare. We herein report a case involving a 51-year-old man with a posterior mediastinal mass. The mass was dissected by thoracoscopy through the eighth intercostal space. Pathological examination led to a definitive diagnosis of a primary mediastinal chondroma with no criteria of malignancy. Preoperative diagnosis of a posterior mediastinal soft tissue chondroma is not easy because of its rarity and lack of typical features other than calcification. When a posterior mediastinal well-circumscribed soft tissue mass contains calcification and shows no obvious enhancement, the possibility of a soft tissue chondroma should be considered.

Context Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome, usually caused by small, benign, and slow-growing phosphaturic mesenchymal tumors. Clinically, TIO is characterized by renal phosphate leak, causing hypophosphatemia and osteomalacia. This review was performed to assess the clinical characteristics of TIO patients described worldwide so far. Evidence Acquisition On June 26, 2021, a systematic search was performed in Medline, Google Scholar, Google book, and Cochrane Library using the terms: “tumor induced osteomalacia,” “oncogenic osteomalacia,” “hypophosphatemia.” There were no language restrictions. This review was performed according to Preferred Reporting Items for Systematic reviews and Meta-Analyses criteria. Evidence Results Overall, 1725 TIO cases were collected. TIO was more frequent in adult men, who showed a higher incidence of fractures compared with TIO women. The TIO-causing neoplasms were identified in 1493 patients. The somatostatin receptor-based imaging modalities have the highest sensitivity for the identification of TIO-causing neoplasms. TIO-causing neoplasms were equally located in bone and soft tissues; the latter showed a higher prevalence of fractures and deformities. The surgery is the preferred TIO definitive treatment (successful in > 90% of patients). Promising nonsurgical therapies are treatments with burosumab in TIO patients with elevated fibroblast growth factor-23 levels, and with radiolabeled somatostatin analogs in patients with TIO-causing neoplasm identified by somatostatin receptor-based imaging techniques. Conclusion TIO occurs preferentially in adult men. The TIO clinical expressiveness is more severe in men as well as in patients with TIO-causing neoplasms located in soft tissues. Treatments with burosumab and with radiolabeled somatostatin analogs are the most promising nonsurgical therapies.

The case of an 82-year-old man who suffered from bone pain is reported. This was due to osteomalacia with hypophosphatemia. The cause was renal phosphate wasting mediated by fibroblast growth factor 23 (FGF-23) with oncogenic osteomalacia. The mesenchymal tumor could be detected at the elbow by positron emission tomography-computed tomography (PET/CT) scanning with 68 Ga-DOTATATE. After resection of this hemangiopericytoma (phosphaturic mesenchymal tumor, PMT) the phosphate level quickly returned to normal.Berichtet wird der Fall eines 82-jährigen Mannes mit Knochenschmerzen. Es bestand eine Osteomalazie bei Hypophosphatämie. Als Ursache zeigte sich ein Fibroblast-growth-factor-23(FGF-23)-vermittelter renaler Phosphatverlust bei onkogener Osteomalazie. Der mesenchymale Tumor konnte mit einer

Primary cutaneous sarcomas are a heterogenous group of malignant soft tissue tumours arising in the dermal and subcutaneous layers of the skin. These tumours are rare and have a variety of clinical manifestations. They differ from deep soft tissue sarcomas in terms of prognosis, which for most types of cutaneous sarcomas is favourable. The tumours are primarily managed by complete surgical excision with margin control. The purpose of this review is to present some of these rare tumors and describe their management.

肿瘤性骨软化症（TIO）是一种罕见的副肿瘤综合征，由于肿瘤分泌调磷因子增多，引起肾脏排磷增加，造成的获得性代谢性骨病。TIO的肿瘤大多数为间叶组织来源的良性肿瘤，通常位于四肢或颅面区域。现收集1例由罕见的嗜酸性实性和囊性肾细胞癌（eosinophilic solid and cystic renal cell carcinoma，ESC-RCC）导致的肿瘤性骨软化症的会诊病例，并分析其临床病理特征，提高对两种疾病的临床病理特征认识，并证实两者之间存在相关性，以减少漏诊、误诊。.

The self-limited nature of nodular fasciitis (NF) is well-known but its precise mechanism has not yet been clarified. We observed that "young" NF (preoperative duration 3 months) (similar to 20%). Thus, we hypothesized that our original observation may reflect a connection with the self-limited nature of NF. Seventeen cases with reliable data concerning the onset were selected, thus approximating the lifetime of each tumor. Besides the USP6 interphase FISH examination, we also checked the most common MYH9-USP6 fusion using RT-PCR. Because of the known pathways of the tumorigenesis of NF, the mRNA level of USP6, TRAIL, IFN-beta, JAK1, STAT1, STAT3, JUN, and CDKN2A was measured using qRT-PCR. Regarding proteins, USP6, p16, p27, TRAIL, and IFN-beta were examined using immunohistochemistry. Targeted gene panel next-generation sequencing (NGS) of three cases was additionally performed. We found a strong negative correlation (p = 0.000) between the lifetime and percentage of USP6 break-apart signals and a strong positive relationship (p = 0.000) between USP6 break-apart signals and mitotic counts. Results of immunostainings, along with qRT-PCR results, favored the previously-suggested USP6-induced negative feedback mechanism through activation of TRAIL and IFN-beta, likely resulting in apoptosis and senescence of tumor cells harboring USP6 fusions. Targeted-NGS resulted in the detection of several variants, but no additional recurrent changes in the pathogenesis of these tumors. We revealed on a cellular level the USP6-induced negative feedback mechanism. In conclusion, we emphasize that in "old" NF, the percentage of USP6 break-apart FISH signals can be as low as 14-27% which can be very important from a differential diagnostic point of view. We emphasize that a careful examination and interpretation of the NGS data is needed before clinical decision-making on treatment.

Primary cutaneous marginal zone lymphoma (PCMZL) is a low-grade B-cell lymphoma that arises in the skin. An adolescent male presented with dermal nodules on the arms, legs, and back with a positive Darier sign, ultimately diagnosed as PCMZL. The nodules demonstrated a partial response to doxycycline in the setting of prior Lyme disease followed by a complete response to rituximab.

CASE This is a case of a 44-year-old man with 10 years of history of painful callus-like swellings of bilateral index fingers. Sudden enlargement of the left index finger prompted biopsy, which revealed aggressive digital papillary adenocarcinoma (ADPA) that was treated with partial amputation. Biopsy of the contralateral finger revealed acanthotic skin with no evidence of malignancy. CONCLUSION Several case reports cite antecedent insult and chronic swelling before diagnosis. We describe a case of bilateral lesions with similar gross appearances, a long history of occupational repetitive trauma, and sudden enlargement of 1 lesion leading to the diagnosis of ADPA.

A 39-year-old man with bone pain underwent Tc-MDP bone scan to assess skeletal lesions, which demonstrated multiple fractures and a focus of subtle extraosseous activity in the left thigh. A Tc-hynic-octreotide imaging was performed due to the suspected diagnosis of tumor-induced osteomalacia, which revealed a hypermetabolic subcutaneous nodule in the left thigh, which exactly corresponded to the same site of MDP activity. Biopsy confirmed the subcutaneous nodule as the culprit tumor of tumor-induced osteomalacia. Bone scan, as a conventional imaging, provided useful information for detecting culprit tumor as shown in our case.

Shoulder lesions range from tumor-like lesions such as simple bone cysts to aggressive high-grade sarcomas. The clinical presentation is often nonspecific with shoulder pain as the primary complaint, which may lead to a delayed or missed diagnosis. Delayed diagnosis or a poorly planned biopsy of a malignant shoulder lesion can have a detrimental effect on the patient's prognosis and treatment options. Because the initial patient assessment is crucial for successful treatment, knowledge of the key features of common shoulder tumors and tumor-like conditions can help determine the diagnosis and treatment plan. This article reviews the key features and treatment options of the more commonly encountered benign and malignant shoulder bone and soft-tissue tumors and tumor-like conditions.

Tumor-induced osteomalacia (TIO) is rare paraneoplastic disorder generally caused by small benign neoplasm. Somatostatin receptor imaging has emerged as imaging of the choice in the localization of the causative tumors in new patients with clinical diagnosis of TIO. An accurate localization of the causative tumor using somatostatin receptor imaging followed by successful surgical removal offers cure of the disease. In small percentage of the patients, however, there can be recurrent disease after the surgery. In this retrospective investigation, we tried to assess whether somatostatin receptor imaging using Tc-HYNIC-TOC (Tc-hydrazinonicotinyl-Tyr3-octreotide) is also useful in patients with recurrent TIO after initial successful surgery.The images of Tc-HYNIC-TOC images and clinical charts of total 18 patients with suspected recurrent TIO were retrospectively reviewed. The image findings were compared with the clinical chart, which include clinical follow-up and subsequent imaging and surgery.Among all 18 patients, Tc-HYNIC-TOC imaging results were negative in 5 of them. Among these 5 patients with negative imaging study, the causes of recurrent symptoms and hypophosphatemia in 3 patients were eventually found unrelated to TIO. Tc-HYNIC-TOC successfully identified either recurrent causative tumors in the same location (n = 10) or different causative tumor in other locations (n = 3) in 13 patients, which rendered a sensitivity of 86.7% (13 of 15).The efficacy of Tc-HYNIC-TOC imaging in the evaluation of patients with potential recurrent TIO is compatible to that with new patients who never received surgical resection for the culprit tumors. It can play an important role in known TIO patients who were suspected to have recurrent disease.

Objective Ga-DOTATATE PET/CT is currently the most common imaging modality in localizing culprit tumors, which can result in tumor-induced osteomalacia (TIO). Fracture, which is one of the most common consequences of the TIO, can also lead to increased Ga-DOTATATE activity and potentially affect the accuracy of Ga-DOTATATE PET/CT imaging. The aim of this investigation is to evaluate whether the increased Ga-DOTATATE activity at the sites of the fracture will cause interpretation difficulty in the localizing the culprit tumor causing TIO. Method The images of Ga-DOTATATE PET/CT scan from a total of 54 patients who had multiple foci of increased Ga-DOTATATE PET/CT on PET/CT were retrospectively analyzed. Not only was the intensity of the activity on PET but also the appearance of the activity on CT taken into consideration when the interpretation of the images occurred. The results from imaging analysis were compared with the clinical chart record. All patients had tentative clinical diagnosis of TIO. Results The causative tumors in 53 patients were eventually identified. In 1 patient, the causative tumor was not identified. Among the 53 patients with confirmed TIO, 52 tumors were accurately localized. Conclusions Mild activity at the sites of fracture is not a major challenging factor in the interpretation of Ga-DOTATATE PET/CT in the evaluation of TIO when both intensity on PET and morphology on CT were assessed.

Background Verrucous venous malformation (VVM), previously called "verrucous hemangioma," typically involves the dermis and the subcutaneous fat. We have encountered patients with VVM confined to the hypodermis. Materials and methods During a nearly 20-year period, 13 patients, aged 2-17 years, presented with a subcutaneous mass in the limb without clinically obvious epidermal alterations. Consequently, operative excisions did not include the skin. Results Histopathologically, the specimens were composed of blood-filled channels with morphologic characteristics of capillaries and veins that infiltrated adipose tissue. Aggregates often formed nodules with variable fibrosis and a component of large and radially oriented vessels. A diagnosis of VVM was supported by endothelial immunopositivity for GLUT-1 (25%-75% immunopositive channels in 16/16 specimens); D2-40 (1%-25% channels in 14/15 specimens); and Prox-1 (1%-50% of channels in 14/16 specimens). A MAP3K3 mutation was identified by droplet digital PCR in 3 of the 6 specimens. Conclusions Diagnosis of VVM in this uncommon location is challenging because of absence of epidermal changes and lack of dermal involvement. Imaging is not pathognomonic, and mimickers are many. Appropriate immunohistochemical stains and molecular analysis contribute to the correct diagnosis.

In children and adolescents, distinguishing tumor-induced rickets/osteomalacia (TIR/O) from hereditary hypophosphatemic rickets/osteomalacia (HR/O) is a medical challenge. We retrospectively studied 10 Chinese children and adolescents with TIR/O who underwent surgery at a mean age of 17.4 ± 2.1 years and compared their characteristics to 24 age- and sex-matched patients with X-linked hypophosphatemia (XLH). Positive family history of HR/O and dental problems, such as enamel hypoplasia and dental abscess, were reported in 8 (33.3%) and 5 (20.8%) patients with XLX, respectively, but not in patients with TIR/O. In addition, in comparison with XLH patients, TIR/O patients had an older disease onset age (150 versus 24 months, p

朗格汉斯细胞肉瘤（Langerhans cell sarcoma， LCS）是一种罕见的、起源于朗格汉斯细胞的恶性肿瘤。该肿瘤几乎均发生于成人，皮肤及皮下软组织是最常见的好发部位。目前国内外文献，检索共报道皮肤LCS 20余例。本文报道1例原发于皮肤的LCS病例，探讨其诊断与鉴别诊断，以提高对该肿瘤的认识。.

Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome due to a phosphaturic tumor, which overproduces Fibroblast Growth Factor 23 (FGF-23), causing hyperphosphaturia, hypophosphatemia, low 1,25(OH)2D and osteomalacia. Tumor localization is critical, diagnostic delay ranges from 2.5 to 28 years and to date surgical removal is considered effective treatment. We retrospectively evaluated patients with definite diagnosis of TIO referred to a tertiary Rheumatology Center between September 2000 and May 2020, investigating clinical management and disease outcome. We included 17 patients: 10 (58.8%) were females, mean age at diagnosis was 55.3 ± 13.9 years (mean ± standard deviation), with a diagnostic delay from symptoms onset to tumor detection of 6.6 ± 6.25 years. Biochemical data were: serum phosphorus 1.3 ± 0.4 mg/dL (Reference Range: 2.5–4.6), serum 1,25(OH)2D 31.8 ± 22.9 ng/mL (RR: 25–86), intact FGF-23, 358.9 ± 677 pg/mL (RR: 25–45); 24 h-Urine Phosphorus was increased in only 2 patients, while tubular reabsorption of phosphate (TRP) was decreased in all patients confirming a renal phosphate wasting. In 2013 68Ga- DOTA-based PET/CT was introduced in routinely practice and diagnostic delay was consistently reduced (from 8.6 ± 7.9 to 4.3 ± 2.4 years). Thirteen patients underwent surgery, one patient underwent radiofrequency ablation; 3 patients, not eligible for surgery, were treated only with supplements of phosphorus and calcitriol. One was started on Burosumab after several unsuccessful surgical attempts. After surgery or ablation, 8 patients had complete remission, 3 TIO persistence, and 3 had overtime relapse. Relapses were observed only in patients who previously underwent closed biopsy. To our knowledge, this is the widest European cohort of TIO patients in the last two decades. We confirm a usual diagnostic delay and recommend a stepwise diagnostic approach. Tumor biopsy is not recommended due to the potential cell spilling. Surgery is generally considered a definitive treatment, even though other approaches have been successful in curing TIO. Active surveillance on possible recurrence is always needed. Burosumab appears a promising therapy.

Tumor-induced osteomalacia (TIO), also known as oncogenic osteomalacia, is a rare acquired paraneoplastic disease, which is challenging to diagnose and treat. TIO is characterized by hypophosphatemia resulting from excess levels of tumor-secreted fibroblast growth factor 23 (FGF23), one of the key physiological regulators of phosphate metabolism. Elevated FGF23 results in renal phosphate wasting and compromised vitamin D activation, ultimately resulting in osteomalacia. Patients typically present with progressive and non-specific symptoms, including bone pain, multiple pathological fractures, and progressive muscle weakness. Diagnosis is often delayed or missed due to the non-specific nature of complaints and lack of disease awareness. Additionally, the disease-causing tumour is often difficult to detect and localize because they are often small, lack localizing symptoms and signs, and dwell in widely variable anatomical locations. Measuring serum/urine phosphate should be an inherent diagnostic component when assessing otherwise unexplained osteomalacia, fractures and weakness. In cases of hypophosphatemia with inappropriate (sustained) phosphaturia and inappropriately normal or frankly low 1,25-dihydroxy vitamin D, differentiation of the potential causes of renal phosphate wasting should include measurement of FGF23, and TIO should be considered. While patients experience severe disability without treatment, complete excision of the tumour is typically curative and results in a dramatic reversal of symptoms. Two additional key current unmet needs in optimizing TIO management are: (1 and 2) the considerable delay in diagnosis and consequent delay between the onset of symptoms and surgical resection; and (2) alternative management. These may be addressed by raising awareness of TIO, and taking into consideration the accessibility and variability of different healthcare infrastructures. By recognizing the challenges associated with the diagnosis and treatment of TIO and by applying a stepwise approach with clear clinical practice guidelines, patient care and outcomes will be improved in the future.

Traditionally patient owners express their concerns that surgical or diagnostic procedures on a tumor may induce metastasis. In pets, this has been documented in only very rare occasions, e. g. needle path metastases after diagnostic fine needle biopsies of urinary bladder or prostatic tumors. Here, we describe a case of subcutaneous seeding of a feline intracranial grade 1 meningioma 6 months after surgical resection. A 10-year-old male neutered domestic shorthaired cat with typical neurological signs was diagnosed with an extra-axial contrast enhancing mass in the dorsal frontotemporal lobes using magnetic resonance imaging (MRI). Transfronto-parietal bone craniotomy was performed and the 24 × 19 × 22 mm large tumor was largely removed. Tumor recurrence after 12 months resulted in a second surgical tumor removal. In addition, 2 subcutaneous masses of 10 × 4 × 4 mm in size were removed at the site of the original surgical site which were fully separated from the recurring meningeal tumor by the intact frontal bone. Histology and immunohistochemistry suggested the same tumor growth in all 4 masses. Most likely the tumor seeding had been caused during the first surgery. After all, the risk of surgical seeding of a benign tumor seems very low.Patientenbesitzer äußern häufig die Befürchtung, diagnostische oder therapeutische Eingriffe könnten die Ausbreitung von Tumoren begünstigen. Tatsächlich werden derartige Zusammenhänge extrem selten beobachtet, etwa bei Hunden als Nadelpfadmetastasen nach diagnostischer Punktion von Harnblasen- und Prostatatumoren. In diesem Fallbericht stellen wir erstmals eine subkutane Ausbreitung eines intrakraniellen Grad-I-Meningioms 6 Monate nach chirurgischer Entfernung vor. Bei einem 10 Jahre alten, kastrierten Europäisch-Kurzhaar-Kater mit typischen klinischen Auffälligkeiten wurde bei einer magnetresonanztomografischen Untersuchung des Gehirns eine extraaxiale kontrastmittelanreichernde Raumforderung von 24 × 19 × 22 mm dorsal der frontotemporalen Lappen nachgewiesen. Durch eine transfronto-parietale Kraniotomie konnte der Tumor größtenteils entfernt werden. Zwölf Monate postoperativ wiesen klinische Auffälligkeiten sowie eine Kontroll-MRT-Untersuchung auf ein Tumorrezidiv in der Schädelhöhle hin. Zusätzlich fielen 2 je 10 × 4 × 4 mm große, kontrastmittelanreichernde subkutane Umfangsvermehrungen in der Nähe der vorangegangenen Kraniotomie außerhalb der geschlossenen Schädeldecke auf. Zur Entfernung des intrakranialen Rezidivs und der beiden subkutanen Massen erfolgte eine zweite rechtsseitige transfrontale Sinotomie. Histologische und immunhistochemische Untersuchungen ließen auf einen gemeinsamen Ursprung aller 4 Massen schließen. Vermutlich handelt es sich bei den subkutanen Umfangsvermehrungen um die Folge einer mechanischen Verschleppung von Tumorzellen während des ersten Eingriffs. Der Fall unterstützt die grundsätzliche Möglichkeit einer derartigen Verschleppung, wobei das Risiko jedoch bei der Häufigkeit dieses Eingriffs als vernachlässigbar gering einzustufen ist.