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Background: The coexistence of two or more distinct neoplasms within the same anatomical site characterizes collision tumors. While the presence of dual tumors is frequently observed in esophageal cases, the simultaneous occurrence of three distinct tumor types is extremely rare, posing significant challenges for pathological evaluation and diagnosis. Surgical resection remains the primary treatment, with generally favorable outcomes. Case presentation: A 58-year-old male with a two-month history of progressively worsening dysphagia over the past 10 days underwent a gastrointestinal barium meal examination, which revealed an irregular filling defect measuring approximately 89×50 mm in the mid-thoracic esophagus. Subsequent gastroscopic biopsy confirmed undifferentiated pleomorphic sarcoma in the mid-esophageal tissue. As the dysphagia advanced, a partial esophagectomy with lymph node dissection was performed. Postoperative pathology revealed a composite tumor consisting of adenoid cystic carcinoma, undifferentiated pleomorphic sarcoma, and focal squamous cell carcinoma. Squamous cell carcinoma metastasis was identified in one lymph node. No adjuvant therapies, such as chemotherapy, radiotherapy, targeted therapy, or immunotherapy, were administered following surgery. The patient had been under monitoring for 101 months, with no signs of recurrence or metastasis. Conclusion: This case represents the first documented instance of a tripartite collision tumor in the esophagus, composed of undifferentiated pleomorphic sarcoma, squamous cell carcinoma, and adenoid cystic carcinoma, with clear histological distinction. A thorough review of the literature was performed to summarize clinicopathological features. Surgical resection leads to a favorable prognosis. Tumors containing both carcinomatous and sarcomatous elements tend to have a more favorable prognosis compared to those composed entirely of carcinomatous tissue, providing valuable insights for future diagnostic and therapeutic strategies. [ABSTRACT FROM AUTHOR]

Background: Collision tumors are defined as two or more distinctly bordered, mutually invasive tumors in the same anatomical region. Characterized by low incidence and lack of specificity, they often pose a significant challenge to disease diagnosis. Among these, collision tumors in the sella region are incredibly rare. Case description: On 13 June 2023, the Department of Neurosurgery at Drum Tower Hospital admitted a patient with a pituitary adenoma in the sella region complicated by spindle cell sarcoma. After reviewing the literature, no related cases were reported. A patient presenting with complex clinical symptoms and preoperative imaging showing occupancy in the sella region is considered to have a recurrence of pituitary adenoma. After thorough preoperative evaluation and discussion, a trans-sphenoidal approach (with the aid of an endoscope) was performed to resect the pituitary lesions. Combined with postoperative pathological tissue and imaging, the patient was diagnosed with a pituitary adenoma (postoperative recurrence) in the sella region complicated by spindle cell sarcoma. The patient made a fair recovery and was discharged on the 8th postoperative day. Conclusion: This case report aims to elucidate and discuss the diagnosis and screening of rare collision tumors in the sella region to reduce the misdiagnosis rate and provide accurate treatment. [ABSTRACT FROM AUTHOR]

Background/Objective: Collision tumors composed of craniopharyngiomas and pituitary adenomas are extremely rare. We report a collision tumor formed by a papillary craniopharyngioma and a growth hormone-secreting pituitary adenoma, which is the first report of such a tumor, to the best of our knowledge. Case Report: A 49-year-old man presented with 2 months of headaches and blurry vision. An exam demonstrated frontal bossing, enlarged jaw and hands, macroglossia, and bitemporal hemianopsia, and magnetic resonance imaging (MRI) showed a 4.1 cm sellar/suprasellar mass with mass effect on the optic chiasm. The tumor was resected twice via a craniotomy, the second time due to interval growth, with the pathology after both surgeries showing a papillary craniopharyngioma. IGF-1 was 517 ng/mL (68-225) and growth hormone suppression test was positive. Repeat MRI showed residual tumor with ongoing mass effect on the optic chiasm and radiation therapy was initiated. MRI showed interval growth of the mass and IGF-1 rose to 700 ng/mL after which the patient underwent a transsphenoidal resection of the tumor; the pathology showed a residual papillary craniopharyngioma and a PIT1 lineage adenoma with most cells expressing growth hormone. After developing numerous complications, the patient passed away. Discussion: Collision tumors of the sella are often associated with an aggressive clinical course, as they often go undiagnosed preoperatively, thus reducing the likelihood of total resection and leading to higher rates of craniopharyngioma recurrence. Conclusion: A pituitary mass with an aggressive clinical course should prompt a high index of suspicion for a sellar collision tumor, though prognosis remains poor.

Tumor-to-tumor metastasis is a known but rare occurrence and is characterized as 2 distinct tumor types in same anatomic location. We present a rare case of intracranial tumor-to-tumor metastasis of esophageal adenocarcinoma into meningioma. Our case emphasizes the rare occurrence of intracranial tumor-to-tumor metastasis and importance of histology and immunohistochemical analysis in distinguishing between metastasis and meningioma, especially when faced with ambiguous demarcation. Awareness of this occurrence is crucial, given that metastases might be the initial indication of an underlying tumor and it can impact the clinical management decisions.

Key Clinical Message: An 83‐year‐old man presented an elevated skin lesion in the left temporal area. The resected specimen was identified between a basal cell carcinoma and an atypical fibroxanthoma. A final diagnosis of basal cell carcinoma and atypical fibroxanthoma was made. This study reports a rare case of a cutaneous collision. [ABSTRACT FROM AUTHOR]

Collision tumors of the ovaries are rare, with only a few reports in the literature. Adult granulosa cell tumors are a relatively common primary tumor component of previously reported collision tumors. The combination of serous and mucinous tumors with adult granulosa cell tumors has been reported in several cases. On the other hand, mesonephric-like adenocarcinomas are rare neoplasms that commonly arise in the uterine corpus and ovaries. In this report, we present the case of a collision tumor composed of an adult granulosa cell tumor and mesonephric-like adenocarcinoma of the ovary in a 63-year-old woman. The initial magnetic resonance imaging findings showed a cystic mass with an internal hemorrhage, which suggested an adult granulosa cell tumor, and a solid mass with different enhancements. Microscopically, the tumor had two distinct components: An adult granulosa cell tumor and a mesonephric-like adenocarcinoma. Recognizing collision tumors consisting of slow-growing and aggressive tumors may prove beneficial in future diagnostic and treatment strategies. [ABSTRACT FROM AUTHOR]

BackgroundThe coexistence of two or more distinct neoplasms within the same anatomical site characterizes collision tumors. While the presence of dual tumors is frequently observed in esophageal cases, the simultaneous occurrence of three distinct tumor types is extremely rare, posing significant challenges for pathological evaluation and diagnosis. Surgical resection remains the primary treatment, with generally favorable outcomes.Case presentationA 58-year-old male with a two-month history of progressively worsening dysphagia over the past 10 days underwent a gastrointestinal barium meal examination, which revealed an irregular filling defect measuring approximately 89×50 mm in the mid-thoracic esophagus. Subsequent gastroscopic biopsy confirmed undifferentiated pleomorphic sarcoma in the mid-esophageal tissue. As the dysphagia advanced, a partial esophagectomy with lymph node dissection was performed. Postoperative pathology revealed a composite tumor consisting of adenoid cystic carcinoma, undifferentiated pleomorphic sarcoma, and focal squamous cell carcinoma. Squamous cell carcinoma metastasis was identified in one lymph node. No adjuvant therapies, such as chemotherapy, radiotherapy, targeted therapy, or immunotherapy, were administered following surgery. The patient had been under monitoring for 101 months, with no signs of recurrence or metastasis.ConclusionThis case represents the first documented instance of a tripartite collision tumor in the esophagus, composed of undifferentiated pleomorphic sarcoma, squamous cell carcinoma, and adenoid cystic carcinoma, with clear histological distinction. A thorough review of the literature was performed to summarize clinicopathological features. Surgical resection leads to a favorable prognosis. Tumors containing both carcinomatous and sarcomatous elements tend to have a more favorable prognosis compared to those composed entirely of carcinomatous tissue, providing valuable insights for future diagnostic and therapeutic strategies.

BackgroundCollision tumors are defined as two or more distinctly bordered, mutually invasive tumors in the same anatomical region. Characterized by low incidence and lack of specificity, they often pose a significant challenge to disease diagnosis. Among these, collision tumors in the sella region are incredibly rare.Case descriptionOn 13 June 2023, the Department of Neurosurgery at Drum Tower Hospital admitted a patient with a pituitary adenoma in the sella region complicated by spindle cell sarcoma. After reviewing the literature, no related cases were reported. A patient presenting with complex clinical symptoms and preoperative imaging showing occupancy in the sella region is considered to have a recurrence of pituitary adenoma. After thorough preoperative evaluation and discussion, a trans-sphenoidal approach (with the aid of an endoscope) was performed to resect the pituitary lesions. Combined with postoperative pathological tissue and imaging, the patient was diagnosed with a pituitary adenoma (postoperative recurrence) in the sella region complicated by spindle cell sarcoma. The patient made a fair recovery and was discharged on the 8th postoperative day.ConclusionThis case report aims to elucidate and discuss the diagnosis and screening of rare collision tumors in the sella region to reduce the misdiagnosis rate and provide accurate treatment.

A 21-year-old man presented with a 2-day history of cephalalgia and a 1-day history of nausea and vomiting. Neuroradiologic imaging revealed a lesion in the third ventricle accompanied by hydrocephalus. After undergoing a ventriculoperitoneal shunt procedure, the patient experienced relief from symptoms. One-month post-shunt, we excised the tumor. Histopathological examination identified it as a rare collision tumor, composed of a mixture of craniopharyngioma and pilocytic astrocytoma. This is an exceedingly rare type of tumor, with no similar cases reported in the existing literature. [ABSTRACT FROM AUTHOR]

Abstract Background Mature cystic teratoma co-existing with a mucinous cystadenocarcinoma is a rare tumor that few cases have been reported until now. In these cases, either a benign teratoma is malignantly transformed into adenocarcinoma or a collision tumor is formed between a mature cystic teratoma and a mucinous tumor, which is either primarily originated from epithelial-stromal surface of the ovary, or secondary to a primary gastrointestinal tract tumor. The significance of individualizing the two tumors has a remarkable effect on further therapeutic management. Case presentation In this case, a mature cystic teratoma is co-existed with a mucinous cystadenocarcinoma in the same ovary in a 33-year-old Iranian female. Computed Tomography (CT) Scan with additional contrast of the left ovarian mass suggested a teratoma, whereas examination of resected ovarian mass reported an adenocarcinoma with a cystic teratoma. A dermoid cyst with another multi-septate cystic lesion including mucoid material was revealed in the gross examination of the surgical specimen. Histopathological examination revealed a mature cystic teratoma in association with a well-differentiated mucinous cystadenocarcinoma. The latter showed a CK7−/CK20 + immune profile. Due to the lack of clinical, radiological, and biochemical discoveries attributed to a primary lower gastrointestinal tract tumor, the immune profile proposed the chance of adenocarcinomatous transformation of a benign teratoma. Conclusions This case shows the significance of large sampling, precise recording of the gross aspects, histopathological examination, immunohistochemical analysis, and the help of radiological and clinical results to correctly diagnose uncommon tumors.

The mucosa-associated lymphoid tissue (MALT) lymphoma subtype, specifically extranodal marginal zone B-cell lymphoma, is a rare variant. Within this subtype, primary thyroid MALT lymphoma is an uncommon occurrence. The literature provides limited documentation on thyroid MALT lymphomas, as their prevalence is comparatively lower than in other organ sites. The coexistence of papillary thyroid carcinoma (PTC) and thyroid MALT lymphomas is exceedingly rare. It presents a rare case of primary thyroid MALT lymphoma accompanied by PTC, thyroid lymphoma not being considered before surgery. A 64-year-old female patient, who had been experiencing symptoms related to a substantial thyroid tumor for a duration of three years, she refused to do a needle biopsy before surgery and expressed a preference for surgical resection. Consequently, the patient underwent a total thyroidectomy along with lymphadenectomy of the central compartment. A histological examination subsequently confirmed the presence of papillary thyroid carcinoma (PTC) and mucosa-associated lymphoid tissue (MALT) lymphoma. Due to the favorable response of the MALT lymphoma to local treatment and the absence of metastasis in other organs, no further treatment was administered for the MALT lymphoma following the surgery. Currently, the patient exhibits no signs of tumor recurrence based on ultrasound and laboratory evaluations. We also provide an overview of the clinical findings on PTC and MALT lymphoma patients already reported and discuss the possible treatment strategy. [ABSTRACT FROM AUTHOR]

Background The coexistence of two histologically distinct neoplasms in the same area without histological admixture or an intermediate cell population zone represents a rare tumor type called collision tumor. Collision tumor of pituitary adenoma and meningioma has been reported years later following irradiation to pituitary adenoma. However, collision tumor of pituitary adenoma and meningioma in absence of irradiation therapy is extremely uncommon. Case Description We report an unusual case of collision tumor involving diaphragma sella meningioma and pituitary adenoma in a 50-year-old lady without prior radiation therapy. She presented with visual blurring and impaired field of vision. Her preoperative magnetic resonance imaging (MRI) was suggestive of pituitary adenoma. Total excision of the lesion was performed through endoscopic transsphenoidal route. Histological diagnosis was consistent with collision tumor of pituitary adenoma and meningioma. Conclusion Collision tumor comprising of nonfunctioning pituitary adenoma and meningioma is extremely rare. Preoperative MRI may not always be able to distinguish these histologically distinct neoplasms. Hence, histopathological examination is necessary to establish the diagnosis. Endoscopic transsphenoidal approach may suffice in excision of these collision tumors. Close follow-up is necessary to detect tumor recurrence. Though the association of these tumors can be coincidental, casual relationship between the occurrence of collision tumors cannot be totally excluded. [ABSTRACT FROM AUTHOR]

Background: Mature cystic teratoma co-existing with a mucinous cystadenocarcinoma is a rare tumor that few cases have been reported until now. In these cases, either a benign teratoma is malignantly transformed into adenocarcinoma or a collision tumor is formed between a mature cystic teratoma and a mucinous tumor, which is either primarily originated from epithelial-stromal surface of the ovary, or secondary to a primary gastrointestinal tract tumor. The significance of individualizing the two tumors has a remarkable effect on further therapeutic management. Case presentation: In this case, a mature cystic teratoma is co-existed with a mucinous cystadenocarcinoma in the same ovary in a 33-year-old Iranian female. Computed Tomography (CT) Scan with additional contrast of the left ovarian mass suggested a teratoma, whereas examination of resected ovarian mass reported an adenocarcinoma with a cystic teratoma. A dermoid cyst with another multi-septate cystic lesion including mucoid material was revealed in the gross examination of the surgical specimen. Histopathological examination revealed a mature cystic teratoma in association with a well-differentiated mucinous cystadenocarcinoma. The latter showed a CK7−/CK20 + immune profile. Due to the lack of clinical, radiological, and biochemical discoveries attributed to a primary lower gastrointestinal tract tumor, the immune profile proposed the chance of adenocarcinomatous transformation of a benign teratoma. Conclusions: This case shows the significance of large sampling, precise recording of the gross aspects, histopathological examination, immunohistochemical analysis, and the help of radiological and clinical results to correctly diagnose uncommon tumors. [ABSTRACT FROM AUTHOR]

Collision tumors, defined as "two independent neoplasms that occur in close proximity to one another but maintain distinct boundaries," are quite rare. We report an exceptional collision tumor composed of a genetically confirmed malignant glomus tumor and a fumarate hydratase (FH)‐deficient leiomyoma, presenting as a subcutaneous thigh mass in a 38‐year‐old male who was known to have hereditary leiomyomatosis and renal cell carcinoma syndrome. Microscopic examination identified a biphasic subcutaneous mass comprising sheets and nodules of glomus cells, with nuclear atypia and mitotic activity, and fascicles of mitotically inactive smooth muscle with variably pleomorphic nuclei and intracytoplasmic eosinophilic inclusions, features of FH‐deficient leiomyoma. Immunohistochemistry demonstrated loss of FH and robust 2‐succinocysteine expression in the smooth muscle, with a normal (FH‐retained) expression pattern in the glomus tumor. Next‐generation sequencing, performed on the glomus tumor component, identified CARMN::NOTCH2 fusion, characteristic of malignant glomus tumors. Awareness of the distinctive morphologic, immunohistochemical, and molecular genetic features of glomus tumors and FH‐deficient leiomyomas is important for correct clinical management of patients with exceptional collision tumors of this type. [ABSTRACT FROM AUTHOR]

Key Clinical Message An 83‐year‐old man presented an elevated skin lesion in the left temporal area. The resected specimen was identified between a basal cell carcinoma and an atypical fibroxanthoma. A final diagnosis of basal cell carcinoma and atypical fibroxanthoma was made. This study reports a rare case of a cutaneous collision.

Ameloblastoma, a benign epithelial odontogenic tumor, has an intriguing feature by virtue of its diverse histopathologic variants. One such variant that is not yet acclimatized in the literature due to the paucity of cases is “hemangiomatous ameloblastoma” (HA). HA exhibits the histology of conventional ameloblastoma with marked vascularity, which resembles the enamel organ and dental sac. Herein, we present the case of a 33-year-old male patient with swelling of the lower left back region of the jaw for 6 months, which on imaging presented multilocular radiolucency. Incisional biopsy was suggestive of ameloblastoma, and an excisional procedure showed odontogenic epithelial islands with marked vascular proliferation, based on which the diagnosis of HA was rendered. The rarity of this histologic variant and lack of long-term follow-up records in the literature challenges the clinician to predict its biological behavior. Hence, further research is required to understand the same.

Composite pleomorphic xanthoastrocytoma-ganglioglioma (PXA-GG) is an extremely rare central nervous system neoplasm with 2 distinct but intermingled components. Whether this tumor represents a "collision tumor" of separate neoplasms or a monoclonal neoplasm with divergent evolution is poorly understood. Clinicopathologic studies and capture-based next generation sequencing were performed on extracted DNA from all available PXA-GG at 2 medical centers. Five PXA-GG were diagnosed in 1 male and 4 female patients ranging from 13 to 25 years in age. Four arose within the cerebral hemispheres; 1 presented in the cerebellar vermis. DNA was sufficient for analysis in 4 PXA components and 3 GG components. Four paired PXA and GG components harbored BRAF p.V600E hotspot mutations. The 4 sequenced PXA components demonstrated CDKN2A homozygous deletion by sequencing with loss of p16 (protein product of CDKN2A) expression by immunohistochemistry, which was intact in all assessed GG components. The PXA components also demonstrated more frequent copy number alterations relative to paired GG components. In one PXA-GG, shared chromosomal copy number alterations were identified in both components. Our findings support divergent evolution of the PXA and GG components from a common BRAF p.V600E-mutant precursor lesion, with additional acquisition of CDKN2A homozygous deletion in the PXA component as is typically seen in conventional PXA.

We report the case of a 51-year-old woman who was initially hospitalized in the respiratory department with cough and fever. Urinary computed tomography (CT) showed two different incidental masses in the right kidney. The patient underwent a radical right nephrectomy without lymph node dissection and postoperative adjuvant treatment. The pathological examination of the surgical specimens showed a collision tumor composed of a clear cell renal cell carcinoma (CCRCC) and a clear cell papillary renal cell tumor (CCPRCT). To the best of our knowledge, this is the first such case reported to date. No recurrence of local or distant metastasis was found during routine follow-up 14 months after the operation. [ABSTRACT FROM AUTHOR]

Copyright of Osmangazi Journal of Medicine / Osmangazi Tip Dergisi is the property of Eskisehir Osmangazi University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Osmangazi Journal of Medicine / Osmangazi Tip Dergisi is the property of Eskisehir Osmangazi University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Collision tumor comprise of existence of two histologically distinct and separate neoplasms in any organ. Thyroid gland is an uncommon site for these tumors, with frequently involved organs being liver, adrenal and stomach. Even among the synchronous tumors of thyroid, papillary and medullary carcinoma are most commonly reported. The present case reports a rare presentation of a collision tumor comprising of papillary and follicular carcinoma with scalp metastasis from the follicular carcinoma and lymph nodal metastasis from the papillary component. It is essential for the clinician to be aware of such an entity so as to guide further treatment and management. [ABSTRACT FROM AUTHOR]

Ameloblastoma, a benign epithelial odontogenic tumor, has an intriguing feature by virtue of its diverse histopathologic variants. One such variant that is not yet acclimatized in the literature due to the paucity of cases is "hemangiomatous ameloblastoma" (HA). HA exhibits the histology of conventional ameloblastoma with marked vascularity, which resembles the enamel organ and dental sac. Herein, we present the case of a 33-year-old male patient with swelling of the lower left back region of the jaw for 6 months, which on imaging presented multilocular radiolucency. Incisional biopsy was suggestive of ameloblastoma, and an excisional procedure showed odontogenic epithelial islands with marked vascular proliferation, based on which the diagnosis of HA was rendered. The rarity of this histologic variant and lack of long-term follow-up records in the literature challenges the clinician to predict its biological behavior. Hence, further research is required to understand the same. [ABSTRACT FROM AUTHOR]

Collision tumors involving the metastasis of malignant neoplasms to pituitary neuroendocrine tumors (PitNETs) are extremely rare. We herein report a case involving a patient with lung adenocarcinoma metastasis within a PitNET who exhibited relatively rapid progression of neurological symptoms. A 75-year-old man who underwent tumor resection 36 and 18 years prior to presentation for bladder and colon cancer, respectively, without recurrence presented with bitemporal hemianopsia, ptosis, and diplopia of the right eye. Subsequent magnetic resonance imaging (MRI) revealed a tumor 3.2 cm in diameter that extended from the anterior pituitary gland to the suprasellar region. Gadolinium-enhanced MRI of the tumor showed heterogeneous contrast enhancement. Considering the relatively rapid progression of neurological symptoms, semi-emergency endoscopic endonasal transsphenoidal surgery was performed. Histopathological examination revealed a group of thyroid transcription factor-1- and napsin A-positive papillary proliferating cells intermingled with α-subunit- and steroidogenic factor-1-positive PitNET cells. Thus, the patient was diagnosed with lung adenocarcinoma metastasis within a gonadotroph PitNET. Genetic testing revealed the presence of an EGFR (Ex-19del) mutation, after which chemotherapy was initiated. Additional stereotactic radiotherapy was performed for the residual tumor in the sella turcica. With continued chemotherapy, good control of both the primary and metastatic tumors was noted after 24 months after surgery. Cases of malignant neoplasm metastasis within a PitNET are difficult to diagnose. In the case of a sella turcica tumor with relatively rapid progression of neurological symptoms, early surgical intervention is recommended given the possibility of a highly proliferative tumor and the need to obtain pathologic specimens.

Finding 2 different histological tumor types at the same site is extremely unusual, especially in patients with no history of radiation exposure or a family history of cancer. We describe a rare case of co-occurrence of meningioma and squamous cell carcinoma at the same site. A 67-year-old woman with a 6-month headache and a verrucous ulcerative mass on her frontoparietal region is the subject of this case study. Her medical history and her family’s medical history are both blank. Her bilateral frontoparietal regions were found to have large heterogeneous lesions with areas of necrosis and superficial ulceration on radiological examination. An extensive heterogeneous extra-axial lesion was discovered during further radiological analysis in the left parasagittal region. Histopathologic examination revealed an impinging tumor consisting of a meningioma and squamous cell carcinoma at the same site. It is extremely uncommon to have multiple primary scalp cancers of different cell types present at the same time. To identify these cancers and choose the best treatments, clinicians will benefit from the information in our case reports.

Collision tumors of the ovaries are rare, with only a few reports in the literature. Adult granulosa cell tumors are a relatively common primary tumor component of previously reported collision tumors. The combination of serous and mucinous tumors with adult granulosa cell tumors has been reported in several cases. On the other hand, mesonephric-like adenocarcinomas are rare neoplasms that commonly arise in the uterine corpus and ovaries. In this report, we present the case of a collision tumor composed of an adult granulosa cell tumor and mesonephric-like adenocarcinoma of the ovary in a 63-year-old woman. The initial magnetic resonance imaging findings showed a cystic mass with an internal hemorrhage, which suggested an adult granulosa cell tumor, and a solid mass with different enhancements. Microscopically, the tumor had two distinct components: An adult granulosa cell tumor and a mesonephric-like adenocarcinoma. Recognizing collision tumors consisting of slow-growing and aggressive tumors may prove beneficial in future diagnostic and treatment strategies.

Collision tumors are rarely reported in patients with von Hippel-Lindau (VHL) disease, even though VHL patients often present with multi-organ tumor syndromes, like hemangioblastoma and renal cell carcinoma (RCC). Hemangioblastoma is rarely located in a supratentorial location, and intracranial lateral ventricular is also not a common site of metastasis for RCC. It is extremely rare for the two tumors to collide in the supratentorial area. We report a 64-year-old man with a history of clear cell RCC who presented with a sudden headache. The brain magnetic resonance imaging revealed that there was a cystic-solid mass in the intracranial lateral ventricular trigone. Histopathologically, the tumor consisted of two distinct components, most of which showed the typical morphology of hemangioblastoma. However, there were a few acinar structures composed of clear cells scattered in hemangioblastoma, and these acinar structures were subsequently confirmed as clear cell RCC. The genetic testing confirmed that the patient had VHL disease with de novo somatic mutation. Based on our case report, we systematically reviewed the characteristics of collision tumor composed of hemangioblastoma and metastatic RCC in VHL patients. The special growth site of our case is the first report of this kind of collision tumor, and can also help enrich our understanding of VHL disease and collision tumor.

Abstract Background Nasopharyngeal carcinoma (NPC) is more common in men aged 40 to 59, and radiotherapy is an effective treatment. Nasopharyngeal lymphoma (NPL) is rare, and the coexistence of nasopharyngeal mantle cell lymphoma (MCL) and NPC is even rarer. A collision tumor is a rare type of tumor that refers to two or more different tumors occurring in the same organ. No reports to date have described a collision tumor of NPC and MCL occurring within the same nasopharyngeal mass. We herein report the successful treatment of a unique case of synchronous coexistence of NPC and MCL occurring in the nasopharynx of a Chinese man. Case presentation A 58-year-old man presented with a 5-month history of swallowing discomfort. Biopsy was performed under nasopharyngeal endoscopy, and histopathology revealed NPC. Magnetic resonance imaging revealed lesions in the nasopharynx, oropharynx, and tonsils, as well as enlarged lymph nodes in the parotid gland, posterior ear, and neck. This may be a synchronous dual primary tumor coexisting with NPC and NPL. Pathology consultation confirmed that the biopsy specimen of the nasopharynx was a collision tumor of NPC and MCL. Positron emission tomography computed tomography (PET-CT) revealed thickening of the posterior wall of the nasopharynx, which was considered NPC with lymphoma. The enlargement of the pharyngeal lymph ring and multiple hypermetabolic lymph nodes were evaluated as lymphoma infiltration. The patient received two courses of R-CHOP chemotherapy (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) followed by head and neck radiotherapy. At the time of this writing, he had remained alive without recurrence for 61 months since the initial treatment and was still undergoing follow-up. Conclusions It is very important to correctly recognize collision tumors. Magnetic resonance imaging helps identify different components of collision tumors. Pathological examination helps to confirm the diagnosis. Histological examination reveals different components, and PET-CT can help determine the extent of the lesion. Dose-adjusted chemotherapy combined with radiotherapy may have promising herapeutic effects, but additional case studies are needed to confirm.

Introduction Collision tumors are a rare phenomenon defined as two or more histologically distinct tumors that are in contact with each other. Case presentation The patient was a man with a history of end‐stage diabetic nephropathy under hemodialysis treatment for 15 years. A plain computed tomography scan showed a 4.3 cm mass with obscured margins in the right perirenal fat of the lower pole kidney. On T2‐weighted magnetic resonance imaging, the lesion showed heterogeneous signal intensity with a partially cystic component. A radical nephrectomy was performed. Histopathological and immunohistochemical examination revealed collision tumors constituted of a spindle cell lipoma covering the kidney surface underneath the perirenal fat and diffusely distributed acquired cystic disease‐associated renal cell carcinoma in the renal parenchyma. Conclusion We report the first case of collision tumors comprising spindle cell lipoma and acquired cystic disease‐associated renal cell carcinoma.

Abstract Background Papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC) are common differentiated thyroid cancers, but the detection of a collision tumor is an extremely rare event. Case presentation The patient was a 69-year-old Japanese female with multiple cervical lymph node swellings and a thyroid tumor. Preoperative fine needle aspiration cytology of the enlarged lymph node revealed a cytological diagnosis of papillary thyroid carcinoma (PTC). A total thyroidectomy, right cervical dissection and paratracheal dissection were performed. Histopathological and immunohistochemical analyses of resected specimens revealed a collision tumor of PTC and FTC. Multiple metastases of papillary carcinoma were found in the dissected lymph nodes. In the PTC lesion, IHC for BRAF (V600E) was positive but negative for the FTC lesion. Genetic analyses further revealed a TERT promoter C228T mutation in PTC and a NRAS codon 61 mutation in FTC. The patient died of recurrent cancer 8 months after surgery. Conclusions A case of a collision tumor of PTC and FTC is very rare, and even fewer cases have been subjected to genetic scrutiny. The present case was successfully diagnosed by pathological examination using immunohistochemical and genetic analyses. The TERT promoter mutation in the PTC lesion was consistent with the aggressive behavior of the cancer.

The coexistence of multiple primary malignant tumors in an organ is rare. This includes the extremely rarely reported combination of gastric adenocarcinoma and gastric MALT-type lymphoma as synchronous tumors. We describe a case of a 72-year-old man diagnosed with this combination. He had no remarkable medical history and came to our hospital because of discomfort in the gastric area. Although the biopsy revealed adenocarcinoma only, the microscopic findings after partial gastrectomy incidentally showed additional lymphoma that was subsequently confirmed by immunohistochemistry as MALT-type lymphoma. This case study and literature analysis aims to raise awareness of the possibility of synchronous malignant neoplasm in the stomach to enhance preoperative diagnosis.

Abstract Background Epstein–Barr virus (EBV)-associated gastric cancer exhibits distinct clinicopathologic characteristics, showing a good response to immune checkpoint inhibitors and a favorable prognosis. However, gastric cancer comprising distinct EBV-positive and -negative components in a single mass have been rarely reported, and their detailed genetic characteristics have not yet been investigated. Therefore, we reported the case of gastric cancer exhibiting distinct EBV-positive and -negative areas and further investigated its genetic characteristics. Case presentations A 70-year-old man underwent distal gastrectomy for gastric cancer, which was detected during a routine health check-up. EBV-encoded RNA in situ hybridization revealed distinct EBV-positive and -negative components at each other’s borders, morphologically consistent with collision tumor. We separately sequenced EBV-positive and -negative tumor areas through whole exome sequencing (WES) with matched normal tissue. Remarkably, both EBV-positive and -negative areas shared pathogenic mutations of ARID1A, KCNJ2, and RRAS2. Furthermore, they shared 92 somatic single nucleotide variants and small insertion or deletion mutations, of which 32.7% and 24.5% are EBV-positive and -negative tumor components, respectively. Conclusions WES results suggested that gastric cancer with distinct EBV-positive and -negative tumor components, formerly categorized as a collision tumor, can be clonally related. EBV-negative tumor component might be associated with loss of EBV during tumor progression.

Glioblastoma (GBM) is a malignant primary brain cancer, among the most devastating and lethal diseases of the central nervous system. Similarly, malignant melanoma (MM) is responsible for most skin cancer–related deaths. A link between those 2 aggressive cancers has not yet been established. We present here a systematic review of the literature and an exemplificative case. A systematic review of the literature was conducted to assess possible commonalities between MM and GBM. An exemplificative surgical vignette of a 73-year-old patient with the occurrence of a frontobasal GBM after surgical removal of a metastasis of MM in the same location was then detailed. Fifteen studies published in the English international literature support a link between MM and GBM, both based on epidemiologic and pathophysiologic/genetic aspects. This theory is reinforced by our surgical vignette of a collision tumor with the occurrence of both tumors in the same location several years apart. The evidence reported in the literature, as well as our surgical vignette, support a likely link between the pathogenesis of GBM and MM. [ABSTRACT FROM AUTHOR]

Background: The definition of "collision tumor" is the coexistence of two histologically and morphologically distinct tumors within the same anatomical area without histological admixture. Collision tumors featuring primary squamous cell and adenoid cystic carcinomas of the hypopharynx, combined with synchronous esophageal carcinoma, are very rare. Methods: We describe a patient with a collision tumor of the hypopharynx and synchronous esophageal carcinoma who underwent partial laryngectomy, with preservation of laryngeal function, and radical esophageal resection featuring esophageal reconstruction using a gastric tube. Surgery was successful. Results: Postoperative radiotherapy was recommended after surgery; the patient exhibited no recurrence or distant metastasis to the 17‐month follow‐up. Conclusion: To the best of our knowledge, this is the first report of collision of primary squamous cell carcinoma and adenoid cystic carcinoma in the hypopharynx and synchronous esophageal carcinoma. We performed appropriate surgery and prescribed postoperative radiotherapy. This preserved laryngeal function. [ABSTRACT FROM AUTHOR]

Background: The co-occurrence of two histologically distinct tumors in the same region separated by a transitional cell population zone or without any histological mixing is known as a true collision tumor. Meningioma, the most common benign intracranial neoplasm, arises from meningothelial cells while a cerebral cavernoma is a benign vascular hamartoma.Case reportWe report a case of a 40-year-old female who presented with right body weakness and seizures. After gross total resection of both tumors, histological examination was consistent with a WHO grade I meningothelial meningioma and cavernous angioma completely separated by gliotic tissue. On subsequent follow-ups, the patient had an improvement of motor power from 0 to 4 out of 5 in the affected extremities and was seizure free without the use of medication. Conclusion: This patient had no risk factors for the development of this association. We believe the total removal of both tumors resulted in the total seizure control of this patient.

Background: Nasopharyngeal carcinoma (NPC) is more common in men aged 40 to 59, and radiotherapy is an effective treatment. Nasopharyngeal lymphoma (NPL) is rare, and the coexistence of nasopharyngeal mantle cell lymphoma (MCL) and NPC is even rarer. A collision tumor is a rare type of tumor that refers to two or more different tumors occurring in the same organ. No reports to date have described a collision tumor of NPC and MCL occurring within the same nasopharyngeal mass. We herein report the successful treatment of a unique case of synchronous coexistence of NPC and MCL occurring in the nasopharynx of a Chinese man. Case presentation: A 58-year-old man presented with a 5-month history of swallowing discomfort. Biopsy was performed under nasopharyngeal endoscopy, and histopathology revealed NPC. Magnetic resonance imaging revealed lesions in the nasopharynx, oropharynx, and tonsils, as well as enlarged lymph nodes in the parotid gland, posterior ear, and neck. This may be a synchronous dual primary tumor coexisting with NPC and NPL. Pathology consultation confirmed that the biopsy specimen of the nasopharynx was a collision tumor of NPC and MCL. Positron emission tomography computed tomography (PET-CT) revealed thickening of the posterior wall of the nasopharynx, which was considered NPC with lymphoma. The enlargement of the pharyngeal lymph ring and multiple hypermetabolic lymph nodes were evaluated as lymphoma infiltration. The patient received two courses of R-CHOP chemotherapy (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) followed by head and neck radiotherapy. At the time of this writing, he had remained alive without recurrence for 61 months since the initial treatment and was still undergoing follow-up. Conclusions: It is very important to correctly recognize collision tumors. Magnetic resonance imaging helps identify different components of collision tumors. Pathological examination helps to confirm the diagnosis. Histological examination reveals different components, and PET-CT can help determine the extent of the lesion. Dose-adjusted chemotherapy combined with radiotherapy may have promising herapeutic effects, but additional case studies are needed to confirm. [ABSTRACT FROM AUTHOR]

Purpose: Intracranial collision tumor is a rare entity that represents the coexistence of two histopathological different tumor types in the same area without histological admixture or an intermediate cell population zone. So far, several cases of collision tumors with ganglioglioma as its component have been reported in the literature, while supratentorial ependymoma has never been reported as a collision tumor component. We are presenting a unique case of collision tumor in patient without previous history of head trauma, neurological surgery, radiotherapy, or phakomatosis. Methods and results: A 17-year-old male with no previous history of head trauma, neurological surgery, radiotherapy, or phakomatosis was presented to our clinic with grand mal seizure. Brain magnetic resonance imaging with gadolinium contrast was done revealing a contrast-enhancing lesion of right frontal lobe closely related to dura, surrounded by perifocal edema. The patient underwent a gross total tumor resection. Histological examination revealed collision tumor with two distinct components: ganglioglioma and supratentorial ependymoma. Conclusion: To our best knowledge, no previous reports of collision tumor composed of ganglioglioma and supratentorial ependymoma in a single patient have been reported. We believe that this report could significantly contribute to further surgical practice as well as to treatment decision for these types of collision tumors. [ABSTRACT FROM AUTHOR]

Perivascular epithelioid cell tumors are very rare mesenchymal neoplasms arising in various locations, such as the female genital tract, kidney, lung, prostate, bladder, pancreas, soft tissues, and bone. They possess a unique immunophenotype, coexpressing myogenic and melanocytic markers; molecular findings include mutations of tuberous sclerosis complex and translocations of transcription factor E3, a member of the microphthalmia transcription factor gene family. We herewith report a uterine collision tumor consisting of a perivascular epithelioid cell tumor and amoderately differentiated endometrial endometrioid carcinoma in a patient with genetically proven tuberous sclerosis; two leiomyomas were also found in contact with the tumor. Although two such cases one with a benign and another with a malignant perivascular epithelioid cell tumor have previously been reported, ours is, to our knowledge, the first reported in a tuberous sclerosis patient. [ABSTRACT FROM AUTHOR]

Background: Papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC) are common differentiated thyroid cancers, but the detection of a collision tumor is an extremely rare event. Case presentation: The patient was a 69-year-old Japanese female with multiple cervical lymph node swellings and a thyroid tumor. Preoperative fine needle aspiration cytology of the enlarged lymph node revealed a cytological diagnosis of papillary thyroid carcinoma (PTC). A total thyroidectomy, right cervical dissection and paratracheal dissection were performed. Histopathological and immunohistochemical analyses of resected specimens revealed a collision tumor of PTC and FTC. Multiple metastases of papillary carcinoma were found in the dissected lymph nodes. In the PTC lesion, IHC for BRAF (V600E) was positive but negative for the FTC lesion. Genetic analyses further revealed a TERT promoter C228T mutation in PTC and a NRAS codon 61 mutation in FTC. The patient died of recurrent cancer 8 months after surgery. Conclusions: A case of a collision tumor of PTC and FTC is very rare, and even fewer cases have been subjected to genetic scrutiny. The present case was successfully diagnosed by pathological examination using immunohistochemical and genetic analyses. The TERT promoter mutation in the PTC lesion was consistent with the aggressive behavior of the cancer. [ABSTRACT FROM AUTHOR]

Background: Epstein–Barr virus (EBV)-associated gastric cancer exhibits distinct clinicopathologic characteristics, showing a good response to immune checkpoint inhibitors and a favorable prognosis. However, gastric cancer comprising distinct EBV-positive and -negative components in a single mass have been rarely reported, and their detailed genetic characteristics have not yet been investigated. Therefore, we reported the case of gastric cancer exhibiting distinct EBV-positive and -negative areas and further investigated its genetic characteristics. Case presentations: A 70-year-old man underwent distal gastrectomy for gastric cancer, which was detected during a routine health check-up. EBV-encoded RNA in situ hybridization revealed distinct EBV-positive and -negative components at each other's borders, morphologically consistent with collision tumor. We separately sequenced EBV-positive and -negative tumor areas through whole exome sequencing (WES) with matched normal tissue. Remarkably, both EBV-positive and -negative areas shared pathogenic mutations of ARID1A, KCNJ2, and RRAS2. Furthermore, they shared 92 somatic single nucleotide variants and small insertion or deletion mutations, of which 32.7% and 24.5% are EBV-positive and -negative tumor components, respectively. Conclusions: WES results suggested that gastric cancer with distinct EBV-positive and -negative tumor components, formerly categorized as a collision tumor, can be clonally related. EBV-negative tumor component might be associated with loss of EBV during tumor progression. [ABSTRACT FROM AUTHOR]

Collision tumor (CT) is the coexistence of two adjacent but histologically distinct and nonadmixed tumor in the same tissue. We report a rare case of ovarian CT: mature teratoma (MT) with thecoma, as well as provide an extensive review of 47 published cases. Ovarian CTs occur in both pre- and postmenopausal women with nonspecific clinic-radiologic symptoms. Prognosis is dependent on the most aggressive component. All the cases, including the index case, were diagnosed post-operatively. Adequate sampling by pathologists and retrospective review and documentation of image features of histologically diagnosed cases by radiologists will enhance both proper and preoperative diagnosis of this lesion. This is the most extensive review on ovarian CTs to the best of our knowledge. [ABSTRACT FROM AUTHOR]

Abstract Background Collision tumors are composed of two distinct tumor components. Collision tumors composed of pancreatic ductal adenocarcinoma and malignant lymphoma occurring in the pancreas have not been previously described in the scientific literature. In this case report, we describe a unique patient with a collision tumor composed of pancreatic ductal adenocarcinoma and peri-pancreatic mucosa-associated lymphoid tissue (MALT) lymphoma occurring in the pancreas. Case presentation An 82-year-old woman presented to our hospital complaining of dizziness. Computed tomography (CT) and magnetic resonance imaging (MRI) showed a large lymphoid lesion spreading from the peri-pancreatic tissue heading to the hepatic hilar plate, involving the hepatoduodenal ligament and the entire duodenum, also showing a hard tumor in the pancreas head. We performed echo-guided needle biopsies for each tumor and diagnosed a collision tumor composed of pancreatic ductal adenocarcinoma and low-grade B cell lymphoma. The patient underwent pancreaticoduodenectomy. The resected specimen showed an elastic hard tumor, 90 × 75 mm in size, located in the pancreatic head, and a whitish-yellow hard tumor involving the lower bile duct, 31 mm in size, located in the center of the pancreatic head. Pathological and immunohistochemical examination proved that pancreatic ductal adenocarcinoma and MALT lymphoma originating from the peri-pancreatic head collided in the pancreatic head. Conclusions To best of our knowledge, this is the first report of a surgically resected collision tumor of pancreatic ductal adenocarcinoma and MALT lymphoma originating from the peri-pancreatic head. A needle biopsy is useful when inconsistent findings are observed on diagnostic CT and MRI of tumor lesions since there is the possibility of a collision tumor.

Collision tumors are two cancers that coexist in the same anatomical site. The etiopathogenesis of collision tumors remains controversial. Even though collision is uncommon, the association between squamous cell carcinoma and malignant melanoma is very rare compared to basal cell carcinoma and malignant melanoma. Here, we report a case of squamous cell carcinoma with malignant melanoma which was confirmed by histopathological examination and immunohistochemistry. The patient underwent wide local excision and flap cover. This case is reported due to the rarity.

Abstract Background Mucosa-associated lymphoid tissue (MALT) lymphoma is a common, low-grade, malignant B-cell lymphoma. However, simultaneous MALT lymphoma in the thymus and lung is extremely rare, and concomitant adenocarcinoma of the lung is even rarer. Herein, we report a rare case of a collision tumor in which MALT lymphoma was found in both the thymus and lung with Sjögren’s syndrome (SS) and adenocarcinoma in the lung. Case presentation A physical examination of a 32-year-old woman revealed an anterior superior mediastinal space-occupying lesion, and chest computed tomography (CT) indicated a nodular ground-glass opacity and irregular mixed-density focus in the right lung. All lung cancer-related tumor biomarkers were within normal ranges. The thymus and part of the lung tissue were surgically resected. The histopathology and molecular examinations confirmed MALT lymphoma of the thymus and lung with lung adenocarcinoma. SS was also diagnosed. No special postoperative treatment was performed for the MALT lymphoma, and the patient underwent immunosuppressive therapy for SS after 4 months of follow-up observation. Conclusions MALT lymphoma of the thymus and lung tissues has no specific presentation on imaging and is difficult to differentiate from common malignant tumors, and the definite diagnoses of these tumors are highly dependent on histopathological examination in combination with molecular testing and cytogenetics. SS may be an important potential condition for the occurrence of MALT lymphoma in the thymus and lung. Additional similar cases are needed to clarify the biological pathways and potential molecular mechanisms of rare lymphomas and collision tumors.

Abstract Background Collision tumors are a subtype of simultaneous tumors wherein two unrelated tumors collide or infiltrate each other. Collision gastric adenocarcinomas (CGA) are rare and difficult to diagnose, and their clinical implications remain unclear. Herein, we aimed to reveal diagnostic methods for CGA and provide insight into its implications. Case presentation Among 1041 cases of gastric cancers (GCs) resected between 2008 and 2018, we included cases of confirmed CGA. Patients’ backgrounds, preoperative endoscopy findings, macroscopic imaging findings, and histopathology findings [including immunostaining for CK 7, MUC2, and mismatch repair (MMR) proteins] were investigated. The incidence of CGA was 0.5%: 5 of 81 cases having simultaneous multiple GCs. Tumors were mainly in the distal stomach. The CGA in two cases was between early cancers, in two cases was between early and advanced cancers, and in one case was between advanced cancers. There were three cases of collision between differentiated and undifferentiated types and two cases between differentiated types. Immunostaining with CK7 and MUC2 was useful for diagnosing collision tumor when the histology was similar to each other. Among ten GCs comprising CGA, nine tumors (90%) exhibited deficient MMR proteins, suggesting high microsatellite instability (MSI). Conclusions CGA is rare and usually found in the distal stomach. Close observation of shape, optimal dissection, and detailed pathological examination, including immunostaining, facilitated diagnosis. CGAs may have high MSI potential.