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Objective Primary pseudomyogenic hemangioendothelioma (PMH) of bone is an extremely rare vascular neoplasm. We present here a case of primary PMH occurring in the maxilla. Study Design A 34-year-old man was referred to our hospital for treatment because of possible recurrence after surgery and chemotherapy of a right maxillary malignant tumor. Morphologic features, immunophenotypes, and FOSB gene rearrangement status of the surgically sectioned sample were assessed by hematoxylin-eosin staining, immunohistochemistry, and fluorescence in situ hybridization, respectively. Results Morphologically, the tumor cells were arranged in a loose fascicular and sheet-like manner, with a large number of reactive woven bones forming. The most striking feature was the presence of epithelioid cells with abundant brightly eosinophilic cytoplasm, which resembled the rhabdomyoblast in appearance. The tumor was diffusely positive for AE1/AE3, CD31, erythroblast transformation-specific transcription factor, and Friend leukemia integration 1; negative for CD34, CAM5.2, epithelial membrane antigen, and desmin; and had retained expression of integrase interactor 1. The tumor harbored FOSB rearrangement. No distant metastasis was found during the follow-up period (18 months). Conclusions To the best of our knowledge, this case represents the first report of PMH arising in the maxilla. The distinct morphologic features, immunophenotypes, and FOSB rearrangement could help achieve precise diagnosis and prevent misdiagnosis of mimics with overlapping features.

Introduction Rhabdomyosarcoma (RMS) is the malignant tumor of skeletal muscles that origin from rhabdomyoblast. RMS is the most common soft tissue tumor in children, but this is a sporadic condition in adults and only 1% of any solid malignancies of an adult. The most prevalent subtype of RMS in an adult is a pleomorphic type. Presentation of case We reported a case of a 57 years old woman with swelling on the left chest with pain for three years. Physical examination revealed swelling on the left chest with solid consistency and immobile. The thorax CT-scan with IV contrast suspicious soft tissue tumor on the anteromedial of the left chest wall that stuck to the left lung. Discussion Histopathological examination confirmed the pleomorphic subtype of rhabdomyosarcoma. The interdisciplinary idea was reported to be superior to a single therapeutic modality. The patient underwent an incisional biopsy. Conclusion This is a case of pleomorphic rhabdomyosarcoma diagnosed base on histopathology from an incisional biopsy, and IHC performed wide excision gave satisfactory results.

Rhabdomyosarcoma is the commonest malignant soft tissue sarcoma affecting children. It originates from the embryonic mesenchyme precursor of striated muscle and involves the head and neck region as a solitary or multiple skin lesion. A 20-day-old female neonate presented with a cutaneous nodule over left shoulder. Hematoxylin and eosin staining on the biopsy specimen showed malignant small round cell tumor. Immunohistochemistry studies were positive for myogenin (nuclear positivity) and desmin (cytoplasmic positivity). Presentation in the neonatal period is rare and poses a diagnostic and therapeutic challenge. The management involves complete excision of the tumor followed by chemotherapy. Int J Clin Pediatr. 2016;5(3-4):47-50 doi: https://doi.org/10.14740/ijcp254e

The pseudomyogenic hemangioendothelioma (PMH) is a low-grade malignant vascular neoplasm of different tissue planes including skin and soft tissue. Primary tumors in the skeletal muscle and bone have also been diagnosed. The PMH was introduced into the WHO classification of tumors of soft tissue and bone in 2013. This is the first description of oral involvement. A 21-year-old female presented with a 2-month old swelling of her gingiva. The swelling appeared red in color and was soft in consistency. A clinical diagnosis of a pyogenic granuloma was made and an incisional biopsy was submitted for histopathological evaluation. The lesion consisted of a proliferation of spindle and epithelioid looking cells. Cells were arranged in loose fascicles and sheets. Rhabdomyoblast-like cells were also seen. No mitotic figures were present. Lesional cells were reactive to cytokeratin AE1/AE3 and CD31. Lesional cell reactivity to S100 protein, HMB 45, SMA, Desmin and CD34 was negative. Following the diagnosis, a wide excision for clear margins was performed. No recurrence has been reported 2 years since the removal. The PMH is a cutaneous tumor that behaves in an indolent fashion. This is the first report of oral involvement by this neoplasm. Recognition of its histopathological features and immunohistochemical reactivity will prevent misadventures in the diagnosis of oral lesions.

Background Rhabdomyosarcoma is a malignant mesenchymal tumor with skeletal muscle differentiation. Primary cutaneous rhabdomyosarcoma is rare. We report a series of 11 cases of primary cutaneous rhabdomyosarcoma. Methods Cases diagnosed as rhabdomyosarcoma arising in the dermis/subcutis with no identified primary tumor elsewhere were retrospectively reviewed. Follow-up was obtained. Results The tumors occurred in five children and six adults. The adult subset consisted of pleomorphic, epithelioid and not otherwise specified (NOS) subtypes while the pediatric subset showed alveolar and embryonal subtypes. All cases showed immunohistochemical staining consistent with the diagnosis of rhabdomyosarcoma. Three adult cases showed immunoreactivity for cytokeratins (one pleomorphic, one epithelioid and one NOS. Conclusions Primary cutaneous rhabdomyosarcoma shows a bimodal age distribution and male predominance, correlating with rhabdomyosarcoma in deep soft tissue. Follow-up, available on all patients, showed aggressive behavior in both children and adults. Primary cutaneous rhabdomyosarcoma should be considered in the differential diagnosis of tumors with abundant eosinophilic cytoplasm and those with “small round blue cell” morphology. Desmin, myogenin and MYOD1 are a trio of markers with high sensitivity and specificity for primary cutaneous rhabdomyosarcoma. Cytokeratin immunoreactivity in primary cutaneous rhabdomyosarcoma represents a potential diagnostic pitfall in the differential diagnosis with sarcomatoid carcinoma.

Malignant triton tumor (MTT) is an aggressive peripheral nerve sheath tumor with rhabdomyoblastic differentiation. Less than 100 cases have been described, being mostly male children with type 1 neurofibromatosis. We report a 6-year-old female with MTT and no diagnostic criteria for neurofibromatosis type 1. Cytogenetic analysis showed a 46,X,-X[4]/46,XX[16] karyotype. She underwent a transfemoral amputation and chemotherapy and is free of disease 15 months after diagnosis. The few cytogenetic studies of MTT described in the literature have been inconclusive. Further cytogenetic analyses are needed to understand the role of chromosome X monosomy in the pathogenesis of this rare tumor.

Summary Extracardiac rhabdomyomas are rare benign entities that usually occur in the head and neck region. Although genital rhabdomyoma is known to occur in the lower genital tract of young and middle-aged women, involvement of the anatomically adjacent urethra by rhabdomyoma is exceedingly rare. We present a case of genital rhabdomyoma arising from the urethra of an infant girl. The tumor was characterized by the submucosal presence of mature-appearing rhabdomyoblastic cells containing conspicuous cross-striations, with the cells set in a collagenous stroma. Necrosis and mitoses were absent. Skeletal muscle differentiation of the tumor cells was supported by positive immunohistochemical staining for desmin and myogenin. To our knowledge, this is the first case of urethral genital-type rhabdomyoma in a child.

We report a case of high-grade endometrial stromal sarcoma with cytological and immunocytochemical findings. Cytologically, major tumor cells showed round-to-short spindle shapes with round- to oval-shaped nuclei and moderately abundant delicate cytoplasm. Tumor cells with tapered shapes and eccentric nuclei were also observed. A few spindle cells having enlarged cigar-shaped nuclei with conspicuous nucleoli and delicate wispy cytoplasm, which resembled leiomyosarcoma, were intermingled. One rhabdomyoblast cell with both α-sarcomeric muscle actin and myoglobin was also observed. Most of the tumor cells, including the leiomyosarcomatous spindle cells, were positive for CD10, and negative for desmin and h-caldesmon. Accordingly, when relatively monotonous round-to-short spindle tumor cells and taper-shaped tumor cells are observed in the female genital tract, high-grade endometrial stromal sarcoma should be considered in the differential diagnosis. Immunocytochemistry contributed to the correct diagnosis. This case was high-grade endometrial stromal sarcoma with smooth muscle and skeletal muscle differentiation.

Malignant peripheral nerve sheath tumor with rhabdomyoblastic differentiation, malignant triton tumor, has a rare incidence. We report such a case in a 40-year-old male who presented with a mass over the buttock. He was a previously diagnosed case of neurofibroma in the same area. Histomorphology supported by immunostaining with S-100 protein confirmed the diagnosis. Malignant triton tumor has a poor prognosis owing to its aggressive biological behavior. The fact that the presence of this tumor in the buttock region is extremely rare has prompted the authors to report this case.

An ultrastructural study is presented of 8 alveolar rhabdomyosarcomas and 8 embryonal rhabdomyosarcomas, and one mesenchymoma with predominantly rhabdomyoblastic differentiation. Thin and thick myofilaments and Z-lines or Z-like densities were found in all. Intermediate filaments were found in 4 alveolar and 4 embryonal rhabdomyosarcomas. A correlation was noted between the light- and electron microscopic appearance of the tumours regarding the degree of differentiation. A wide differentiation spectrum of the tumour cells was observed which could be correlated partly with normal fetal myogenesis. Ultrastructural differences were demonstrated in the alveolar and embryonal types. Electron microscopy is considered to play an important role in the characterization and diagnosis of rhabdomyosarcoma and is a valuable tool in the differential diagnosis.

The aim of this study is to report the clinicopathologic characteristics of 3 cases of alveolar rhabdomyosarcoma with neuroendocrine/neuronal differentiation. Specimens of 3 cases of alveolar rhabdomyosarcoma were studied using histologic, immunohistochemical, ultrastructural, and molecular genetic techniques. The patients were a 19-year-old man with metastatic alveolar rhabdomyosarcoma in a groin lymph node, a 16-year-old girl with alveolar rhabdomyosarcoma of the perineum, and a 20-year-old man with recurrent orbital alveolar rhabdomyosarcoma. Microscopically, case 1 was composed of compact sheets of medium to large tumor cells. Cases 2 and 3 were small blue round cell tumors. Cases 1 and 3 were solid throughout, whereas case 2 demonstrated alveolar and solid architecture. By immunohistochemistry, the following markers were positive: desmin (3/3), myogenin (3/3), synaptophysin (3/3), and chromogranin (2/3). Ultrastructurally, sarcomeric filaments were seen in all cases, while neuroendocrine granules were detected only in case 1. PAX:FKHR fusion transcript was identified in case 2, case 3 had a variant PAX3 transcript, and case 1 was negative. The data presented expands the known differentiation of alveolar rhabdomyosarcoma.

Purpose. This article reports on a sclerosing perineal-perianal rhabdomyoma in an adult woman. A review of the literature disclosed no reference to this histological form of rhabdomyoma in women. Methods and Results. We describe the case of a 48-year-old woman. At physical examination, a firm nodular lesion was identified in the left lateral perianal-perineal region. Histologically, it comprised rounded and elongated muscle fibers displaying no evident atypia, within a stroma exhibiting marked sclerosis and mild lymphoid infiltrate. At immunohistochemical examination, tumor cells stained for desmin, muscle-specific actin, and myogenin. Conclusions. Skeletal muscle rhabdomyomas are rare benign tumors, generally divided into 3 major categories depending on their clinical and morphological characteristics: fetal, adult, and genital. An unusual histological variant of the genital form has recently been reported in men, characterized by the presence of predominantly mature muscle fibers and marked sclerosis. We document such a lesion in a female patient for the first time.

Animal experiments have shown that carcinogenicity of chemicals is higher in fetal or neonatal periods than adult. We investigated sensitivities to a carcinogen in peri-neonatal rats with a model of sarcomas-induction by a subcutaneous injection of chemo-carcinogen that has rarely done in neonatal rats. Neonatal male SD rats were injected with 7,12-DMBA 10, 100, and 500 μg, which resulted in sarcomas-induction in 0, 62, and 94% of rats. Male SD rats were injected with DMBA 500 μg at 0, 3, 7, 14, and 21 days, which resulted in sarcomas-induction in 94, 70, 64, 50, and 44% of rats. Although the induced sarcomas were occasionally in mixed morphological feature as previous reports for sarcomas of rat, each was immunohistochemically in almost monotonous pattern, and classification was feasible. The incidence of rhabdomyosarcomas was higher in rats neonatally injected with a higher dose of DMBA than a lower dose, and in rats injected at peri-neonatal periods than later periods. In histological observations for the site of injection before overt sarcomas develop, clusters of atypical mesenchymal cells emerged as previous studies, but also those were immunohistochemically differentiated into rhabdomyocytes and other mesenchymal cells. We consider these findings may contribute a little to elucidation of process of sarcomas-induction in rats.

Dedifferentiated areas of dedifferentiated liposarcoma (DDL) usually show malignant fibrous histiocytoma (MFH)- or fibrosarcoma-like features and lack any histologic signs of specific differentiation. However, some reports have demonstrated specific differentiation in these areas, with histologic features resembling those of rhabdomyosarcoma, leiomyosarcoma, and osteosarcoma. We report here a pathologic and genetic analysis of three cases of DDLs with rhabdomyosarcomatous areas. MFH- or fibrosarcoma-like areas of one primary DDL and two recurrent DDLs contained various amounts of rhabdomyoblasts, which were immunoreactive for desmin, myoglobin, muscle actin (HHF-35), and myogenin. An ultrastructural examination demonstrated rhabdomyoblasts with abundant cytoplasm containing thin and thick filaments and Z-bands. By real-time PCR, amplification of mdm2 and cdk4 was confirmed in both well-differentiated and dedifferentiated areas with rhabdomyoblasts of all cases. To our knowledge, only seven cases of DDLs with rhabdomyosarcomatous components have been reported, and furthermore, the genetic profiles of the rhabdomyosarcomatous components in DDLs have not been investigated. This study demonstrates that DDLs with rhabdomyosarcomatous areas have genetic alterations that are common to well-differentiated/dedifferentiated liposarcomas.

A rare case of olfactory neuroepithelioma with rhabdomyoblasts in a 61-year-old man was investigated using electron microscopic and immunohistochemical methods. A large tumor enhanced by gadolinium-diethylenetriamine pentaacetic acid (DTPA) was demonstrated on magnetic resonance imaging (MRI), located within the anterior cranial fossa without bone destruction. The tumor mostly consisted of small cells with scant cytoplasm. Tubular rosettes were often found. Immunoreactivity for cytokeratin and epithelial membrane antigen (EMA) was strongly positive. Most of the tumor cells were shown to be positive for neuron-specific enolase (NSE) and vimentin and weakly positive for synaptophysin and S-100. Rhabdomyoblasts, which showed oval cells with abundant eosinophilic cytoplasm and a nucleus sometimes displaced toward the periphery of the cell body, were frequently intermingled with the tumor cells. The immunoreactivity for myoglobin was frequently positive in these oval cells. The MIB-1 index showed high values, of 20%-40%. About 10% of the tumor cells revealed positivity for p53 protein and vascular endothelial growth factor (VEGF). Ultra-structurally, numerous junctional complexes were observed between cell bodies and processes. The cell processes frequently contained numerous microtubules. There were sometimes numerous filaments with small aggregates of Z-band material and thick filament-ribosomal complexes in the oval cells. They were concluded to be consistent with rhabdomyoblasts on light microscopic and immunohistochemical findings.

McCluggage WG, Lioe TF, McClelland HR, Lamki H. Rhabdomyosarcoma of the uterus: Report of two cases, including one of the spindle cell variant.Most uterine sarcomas fall into the category of leiomyosarcoma, endometrial stromal sarcoma, or undifferentiated sarcoma. Pure rhabdomyosarcomas are extremely rare, although a rhabdomyosarcomatous element may be present as a component of an adenosarcoma or carcinosarcoma (malignant mixed müllerian tumor). This report describes two uterine rhabdomyosarcomas in 28- and 67-year-old women. These were of spindle cell and pleomorphic types, respectively. At presentation the pleomorphic rhabdomyosaroma was stage IV, exhibiting massive pelvic and abdominal dissemination that mimicked an ovarian neoplasm. The spindle cell rhabdomyosarcoma was stage I, being confined to the uterus. Grossly, both uterine tumors had a polypoid appearance. Immunohistochemically, tumor cells were positive with the skeletal muscle markers sarcomeric actin, myoglobin, and myoD1. The patient with stage IV disease died within a short time of diagnosis and the other patient is alive and well at 2 years' follow-up. This report adds to the published literature on uterine rhabdomyosarcomas. This is the first reported uterine case of the spindle cell variant of embryonal rhabdomyosarcoma. Based on these cases and the published literature, rhabdomyosarcoma, especially the pleomorphic variant, appears to be a very aggressive neoplasm with an extremely poor prognosis. Immunohistochemical demonstration of skeletal muscle differentiation is necessary for a definitive diagnosis.

We describe an infant with a congenital polypoid anal mass, diagnosed as botryoid-type embryonal rhabdomyosarcoma. Histological examination revealed myxoma-like appearance and cells with greater differentiation with elongated streaming eosinophilic cytoplasm and one or two nuclei, suggestive of rhabdomyoblasts. Tumour cells were strongly immunoreactive for desmin and 10% of cells displayed immunoreactivity for myoglobin. We present this case with a view to highlighting the benign clinical and histological appearance of botryoid-type embryonal rhabdomyosarcoma. Early biopsy is essential for improving prognosis.

A clear cell rhabdomyosarcoma was studied by light microscopy, histochemistry, immunohistochemistry, and electron microscopy. It was a large, painful left parapharyngeal mass in a 10-year-old boy with intracranial extension and cervical metastatic enlarged lymph nodes. Tumor tissue was macroscopically grayish. At microscopic examination, the architecture was diffuse and focally alveolar. Tumor cells were of three types. Most cells were large, round or polygonal, with abundant clear vacuolated cytoplasm. Fibrils were sometimes found to be present around the nucleus. Nuclei often had irregular outlines and multiple nucleoli. Mitotic activity was high. Some round or elongated cells had eosinophilic fibrillar cytoplasm and were found to have a few double striations. A few cells were round and medium sized with a high nucleocytoplasmic ratio. Periodic acid-Schiff stain demonstrated huge amounts of intracytoplasmic glycogen in clear cells. Tumor cells showed positive immunostaining for muscle markers (desmin, muscle actins, dystrophin). Electron microscopy showed large lakes of glycogen, lipid droplets, and striated muscle features.

Sarcoma botryoides, or embryonal rhabdomyosarcoma, is probably the most common form of rhabdomyosarcoma encountered in gynaecology. 1 The rhabdomyoblast is capable of giving rise to a number of different neoplasms, classified by Horn and Enterline (1958) as embryonal, botryoid, alveolar and pleomorphic. 2 The botryoid turnout consists of embryonal-type cells and originates in a submucosal cellular zone of primitive rhabdomyoblasts, known as the cambium layer of Nicholson. Its classical polypoid or grape-like appearance is related to this submucosal location. Sarcoma botryoides is the most common neoplasm of the lower genital tract in girls under 16 years of age, 3 with 90% of patients presenting before the age of 5 years. 4 Patients seen in late adolescence or older tend to have disease at the upper end of the genital canal; the upper vagina, the cervix, or the uterine corpus. 5 The peak incidence of cervical sarcoma botryoides is the second decade. 6 Eighty per cent of patients present with either abnormal vaginal bleeding or a mass in the vagina, with approximately 75% presenting with Group I disease. In 1975, the Intergroup Rhabdomyosarcoma Study group recommended a staging system for classifying patients with rhabdomyosarcoma (Table 1). This has subsequently been used by authors in describing and detailing cases. 7

Rhabdomyosarcoma has traditionally been subclassified into alveolar, embryonal, and pleomorphic variants. Less commonly, spindle-cell, neuroendocrine, sclerosing, and lipid-rich or clear-cell subtypes are seen. The author recently encountered a myogenic sarcoma, with all the common markers of rhabdomyosarcoma, but expressing the unusual features of alpha-smooth-muscle actin and abundant rough endoplasmic reticulum (rER). This myogenic sarcoma, therefore, exhibited four lines of differentiation, and is documented here. The patient was a 65-year-old man with an inguinal soft tissue mass. Following surgical excision, the patient was given radiotherapy and was well without disease after 6 years. The tumor was positive for vimentin, desmin, alpha-smooth-muscle actin, alpha-sarcomeric actin, myogenin, MyoD1, and CD68. Cytoplasm was dominated by abundant rER intermingled with lipid droplets and lysosomes. Cell surfaces exhibited microvillous processes and focal adhesions, but no lamina. Subplasmalemmal smooth-muscle-type myofilaments with focal densities and rare sarcomeric filaments were seen. The low level of expression of some markers was interpreted as consistent with a poorly differentiated tumor. Given the four lines of differentiation--striated muscle, smooth muscle, fibroblastic, and histiocytic--a name reflecting its phenotype would be pleomorphic rhabdomyosarcoma showing smooth-muscle and fibrohistiocytic differentiation.

A series of 15 cases of rhabdomyosarcoma diagnosed by fine-needle aspiration biopsy (FNAB) and confirmed by histopathology is reviewed. Cytologically, the tumors were composed of a variable mixture of cells, which according to the degree of differentiation were categorized as early, intermediate, or late rhabdomyoblasts. Histologically, the tumors were divided into embryonal 9, monomorphic round cell 4, and alveolar rhabdomyosarcoma 2. Comparison of histological and cytological features revealed that embryonal types were composed mainly of early rhabdomyoblasts. Recognition of these patterns may be helpful in FNAB diagnosis of rhabdomyosarcoma.

An embryonal rhabdomyosarcoma (sarcoma botryoides) of the cervix occurring in a 30-year-old woman is described. In addition to typical areas of the embryonal rhabdomyosarcoma, including cartilaginous elements, the neoplasm was characterised by the presence of foci composed of highly pleomorphic cells. The significance of this finding is uncertain. These foci may represent areas of dedifferentiation in an embryonal rhabdomyosarcoma.

Rhabdomyosarcoma presents special diagnostic problems when it involves the uterine cervix in young children because tumor cells may lack marked atypia and may blend with the normal, immature, condensed, cellular stroma, rendering diagnosis difficult. Myogenic makers are a valuable ancillary technique for establishing a diagnosis of rhabdomyosarcoma. However, desmin positivity has been reported in cervical stromal cells, which can confound diagnosis. To determine whether immunohistochemical markers of skeletal muscle differentiation are helpful in the diagnosis of uterine botryoid rhabdomyosarcoma, we compared the immunohistochemical staining pattern of cervical rhabdomyosarcoma from 3 patients with that of normal uteri from age-matched autopsy controls by using antibodies for desmin, smooth muscle actin, muscle-specific actin, myoD1, myogenin, and WT-1. All tumors demonstrated at least focal immunopositivity for desmin, muscle-specific actin, smooth muscle actin, myoD1, and WT-1, and 1 tumor was also positive for myogenin. Autopsy controls showed only scattered subepithelial stromal immunoreactivity for desmin, muscle-specific actin, smooth muscle actin, and WT-1 and showed cytoplasmic, but not nuclear, immunopositivity for myoD1 and myogenin. Myometrium was diffusely positive for desmin and muscle-specific actin. We conclude that desmin, muscle-specific actin, smooth muscle actin, and WT1 are not specific for discriminating embryonal rhabdomyosarcoma from normal subepithelial cells in the female genital tract of children, although the number of immunopositive cells is consistently larger in rhabdomyosarcoma. Nuclear staining for myoD1 and myogenin appears not to occur in normal tissue, but it may be absent or sparse in embryonal rhabdomyosarcoma. Our findings indicate that, in this anatomic site, the diagnosis of rhabdomyosarcoma and in particular determination of tumor margins remain very reliant on histomorphology.

We report herein the case of a 17-year-old woman with von Recklinghausen's disease who was diagnosed as having a giant malignant Triton tumor located in the anterior mediastinum, which had adhered to the heart and the great vessels. An emergency operation was performed to relieve the tracheobronchial stenosis and congestive heart failure caused by the pressure of the tumor. Extracorporeal circulation was not required and the tumor could be excised only piece by piece. To our knowledge, this is the first report of a malignant Triton tumor being located in the anterior mediastinum.

A unique case of primary myxoid liposarcoma of the thigh, in which focal pleomorphic areas were present containing rhabdomyoblasts, is described. Focal rhabdomyosarcoma in liposarcoma has only rarely been reported previously and only in dedifferentiated liposarcomas of the retroperitoneum. All but one have been recurrences with rhabdomyoblasts being absent in the primary liposarcoma. As rhabdomyoblasts were only focally present, the present case is regarded as liposarcoma with focal divergent rhabdomyoblastic differentiation rather than malignant mesenchymoma.

Rhabdomyosarcomas are classified into three well-defined categories: embryonal, alveolar and pleomorphic rhabdomyosarcoma. Recently, seven cases of an unusual adult type of rhabdomyosarcoma with a prominent hyaline sclerosis have been described. We report the hitherto unreported cytogenetic changes of an adult sclerosing rhabdomyosarcoma. A 79-year-old woman underwent an amputation for a rapidly growing soft tissue mass in the anterior compartment of the right lower leg. The tumor infiltrated the tibia. On histology, a fascicular spindle to round cell proliferation, embedded in a prominent hyaline matrix, was seen. Immunohistochemistry showed focal desmin, myogenin and MyOD1 expression, and electron microscopy revealed Z-band material. Cytogenetic analysis disclosed a 44-49,XX,+del(1)(p22)[2],+11,+16[5],+18[12],+21[3],-22 [cp13] karyotype. Using fluorescent in situ hybridization (FISH) analysis, the tumor cells were negative for FOXO1A-disrupting translocations specific for alveolar rhabdomyosarcoma. The chromosomal composition of malignant cells resembled the pattern of numerical changes frequently observed in embryonal rhabdomyosarcoma, suggesting a close relationship of an adult sclerosing rhabdomyosarcoma with this entity.

Pleomorphic rhabdomyosarcoma is considered rare and controversial, especially in children. Although pleomorphic rhabdomyosarcoma has been observed in children, its sparcity has taken it out of current childhood rhabdomyosarcoma classifications. We report four pediatric cases of pleomorphic rhabdomyosarcoma, review morphologic, immunohistochemical, and ultrastructural features, and discuss the rare need to include this category in children. The Soft Tissue Registry of the Armed Forces Institute of Pathology was searched for cases coded as "pleomorphic rhabdomyosarcoma" from 1970 to the present. Only cases in patients less than 21 years old were included. Clinical data, morphology, and immunohistochemical stains were reviewed and follow-up was obtained. Electron microscopy was performed on two cases. Molecular analysis by polymerase chain reaction was performed on one case with available material. Of four patients included, there were three boys and one girl. Patient ages ranged from 9 months to 10 years (median, 4.5 years). Tumors were located on the chest wall (n = 2) and one each on the upper and lower extremities. Tumor size ranged from 4.0 to 10.0 cm (median, 7 cm). Grossly, the tumors were lobulated and circumscribed. Microscopically, architectural patterns varied from solid to fascicular or storiform. All tumors had large, often multinucleated, polygonal, spindled or strap-like rhabdomyoblasts with abundant eosinophilic cytoplasm. Nuclear characteristics ranged from hyperchromatic to vesicular. Most tumor cells had large prominent nucleoli. Background rhabdomyoblasts varied from spindled to polygonal. No tumors displayed areas typical of embryonal or alveolar rhabdomyosarcoma. All tumors exhibited atypical mitotic figures. Immunohistochemistry revealed that the tumors were positive for the following markers: desmin (3/4), myoglobin (4/4), myoD1 (3/3), myf4 (3/3), and MSA (4/4). The two cases studied by electron microscopy both showed evidence for skeletal muscle differentiation. One case showed no evidence for a t(2;13) or t(1;13) translocation. Two patients were alive with no evidence of disease at 12 and 25 years. One patient was dead of disease at 9 years. Pleomorphic rhabdomyosarcoma is rare but exists in children. The diagnosis should be considered in pleomorphic sarcomas exhibiting skeletal muscle differentiation, which are otherwise devoid of typical areas or chromosomal changes of embryonal or alveolar rhabdomyosarcoma.

In a 5-year-old Holstein cow, a neoplasm composed of a large intramuscular mass and multiple metastases in the lungs and lymph nodes was diagnosed as a pleomorphic rhabdomyosarcoma. This neoplasm was characterized by marked variation in tumor cell size and giant cells with single bizarre nuclei. Although the presence of cross striations and myoglobin could be confirmed, expression of alpha-smooth muscle actin (SMA) was also recognized in a few cells. Neoplastic cells showing intense staining for desmin, vimentin and proliferating cell nuclear antigen irrespective of their size differed from those in an embryonal rhabdomyosarcoma that exhibited a wide spectrum of differentiation, reminiscent of normal skeletal myogenesis. The cellular pleomorphism and SMA expression seemed to be characteristic of deviation from normal muscle cells or satellite cells in adult muscle.

Rhabdomyosarcomas are a heterogeneous group of tumors with respect to their molecular basis, degree of differentiation, histology, and clinical behavior. Because of the wide variation of tumor morphology, it is often difficult to distinguish between the distinct subtypes of rhabdomyosarcomas. By using cryosections of tumor specimens and immunohistochemistry, in the present study we show that strong expression of myogenin in rhabdomyosarcoma is associated with alveolar histology (P =

A case of paratesticular pleomorphic rhabdomyosarcoma, presenting as an ulcerated mass in the left hemiscrotum of an 83-year-old man, is reported. By light microscopy, this neoplasm could not be distinguished from other pleomorphic sarcomas, such as malignant fibrous histiocytoma, leiomyosarcoma, and liposarcoma. Immunohistochemistry showed that most tumor cells were strongly reactive with antibodies directed against myoglobin, desmin, a-sarcomeric actin, and myogenin, whereas x-smooth muscle actin expression was less extensive. Electron microscopic examination demonstrated thick and thin filaments with condensations of electron-dense material reminiscent of structures of Z-lines in the large pleomorphic cells. On the basis of these findings, the neoplasm was classified as a pleomorphic rhabdomyosarcoma. According to a review of the literature, this is the first well-documented example of paratesticular pleomorphic rhabdomyosarcoma in an elderly person.

Malignant mixed mullerian tumors (MMMT) are unusual neoplasms occurring mostly in the uterus. In the ovary, they are very rare and represent fewer than 1% of all ovarian malignancies; in the salpinx, they are even rarer than those of the ovary. We report a carcinosarcoma of the left adnexa having features of neuroendocrine differentiation in a 69-year-old female. The tumor contained both adenocarcinoma and squamous cell carcinoma having dear cell change admixed with an undifferentiated malignant mesenchymal component. The sarcoma components consisted of spindle cells, small-round cells and bizarre giant cells mimicking rhabdomyoblast. Almost all of the carcinomatous glandular components and some foci of the squamous cell and undifferentiated carcinomatous components were focal positive for S-100 protein, chromogranin, neuron specific enolase, synaptophysin and Leu-7. Electron microscopy revealed membrane-bound neurosecretory granules in the cytoplasm of some glandular epithelial cells. Histologically, the tumor involved the left adnexa, abdominal peritoneum, surface of the bladder dome, omentum and left external iliac lymph node (stage IIIc).

Two cases of malignant 'triton' tumour arising within lung parenchyma are described. The patients were a three-year-old child and a 53-year-old man. Both patients presented with shortness of breath and a large intrapulmonary mass on chest X-ray. Neither patient had a history of von Recklinhausen's neurofibromatosis. The lesions were treated by pneumonectomy. Grossly, both tumours presented as large, soft and gelatinous intraparenchymatous masses measuring 130 mm and 80 mm, respectively. Histologically, they were characterized by an atypical spindle cell proliferation embedded in an abundant myxoid stroma. Focal areas of rhabdomyoblastic differentiation characterized by large cells with abundant eosinophilic cytoplasm and occasional cytoplasmic cross-striations could be seen admixed with the atypical spindle cell elements. Immunohistochemical studies showed a focal positive reaction for S-100 protein in the atypical spindle cells embedded within the myxoid stroma, and a strong positive reaction for desmin and myoglobin in the rhabdomyoblastic areas. The child died three months after diagnosis with extension of the tumour into the thoracic cavity. The second patient has been lost to follow-up. Although rare, malignant 'triton' tumour should be considered in the differential diagnosis of primary spindle cell sarcomas of the lung.