Malignant glomus tumor arising in association with a fumarate hydratase-deficient leiomyoma: An unusual collision tumor

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.

Sentinel report of uniquely paired collision tumors: glioblastoma multiforme and coexistent intraventricular subependymoma. Illustrative case

BACKGROUND

The presence of intracranial collision tumors, histologically distinct tumors occurring in anatomical proximity, is quite rare. Herein, the authors describe the sentinel case of a contiguous collision tumor combination consisting of glioblastoma multiforme and intraventricular subependymoma.

OBSERVATIONS

A 67-year-old male presented with several months of progressive fatigue superimposed on more recently noted word-finding difficulty, slight left-sided weakness, and episodic confusion. He was found to have a large right frontal mass abutting the right lateral ventricle with an additional nodular focus of enhancement within the right frontal horn. The patient underwent an awake right frontal craniotomy for gross-total resection of the tumor, noted to be of two distinct histological identities.

LESSONS

Although exceptionally rare, primary glial neoplasms of various histologies can be encountered simultaneously during resection, as in this case of co-occurring glioblastoma of the right frontal lobe and right frontal horn intraventricular subependymoma. Close attention to tumoral locations and the gross appearance of specimens during resection can prime the operative neurosurgeon for success in contributing to accurate diagnoses through sending separate pathological specimens for histological analysis when qualitatively different tissue is suspected.

A Pancreatic Collision Tumor Comprising Mantle Cell Lymphoma and Adenocarcinoma: A Case Report and Literature Review

A collision tumor is a rare clinical condition where two different tumors occur synchronically within a lesion. Pancreatic collision tumors with mantle cell lymphoma (MCL) are extremely rare and have only been reported in one case to date. We herein report an elderly patient with MCL and adenocarcinoma of the pancreas with Ann Arbor stage IV and Union for International Cancer Control stage IIB, respectively. The patient received palliative therapy and died 23 months after the diagnosis. Further research and case studies are required to investigate whether or not MCL-derived cyclin D1 overexpression affects the occurrence/growth of adenocarcinomas.

Hepatocellular carcinoma‑cavernous hemangioma collision tumor: A case report

Collision tumors consisting of hepatocellular carcinoma (HCC) and cavernous hemangioma (CH) are rare and the clinicopathological characteristics or cause of the tumors remain unclear. The present study reports the case of a 71-year-old male patient who was admitted to Sunshine Union Hospital (Weifang, China) due to a liver mass found during a routine physical examination. computed tomography scans showed a main lesion of ~4.0×4.2×3.5 cm in segment IV of the patient's liver and a nodule of ~2.4×2.2×1.3 cm in the lower-left part of the lesion, which was clearly demarcated from the main lesion. The capsule of the lesion was found to be intact during the operation performed to remove the tumor. The final patient diagnosis was of a HCC-CH collision tumor based on pathology. The patient underwent follow-up for 6 months after surgery and no recurrence was observed.

A Rare Presentation of Collision Diffuse Large B-Cell Lymphoma and Hodgkin Lymphoma Treated with R-CHOP and Adjuvant Radiation Therapy

Collision tumors are rare neoplasms displaying two distinct cell populations developing in juxtaposition to one another without areas of intermingling. There are currently no guidelines for the recommended treatment for such rare collision cases. We herein report a unique case of a 45-year-old female who presented with a left-sided palpable inguinal lymph node. A subsequent excisional biopsy yielded a diagnosis of collision lymphoma (CL) of nodular sclerosing Hodgkin lymphoma (HL) and germinal center diffuse large B-cell lymphoma (DLBCL). This case report highlights the challenges in managing CL and the potential efficacy of cyclophosphamide, doxorubicin, vincristine, prednisone, and rituximab regimen (R-CHOP) and adjuvant radiation therapy (RT) in treating this rare condition. Our goal is to enrich the literature with our case on CL in an attempt to progress to a path of ultimately establishing a definitive treatment approach to CL of DLBCL and HL.

Successful surgery with preservation of laryngeal function in a patient with collision primary squamous cell carcinoma and adenoid cystic carcinoma in the hypopharynx and synchronous esophageal carcinoma: A case report

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.

Collision tumor of spindle cell lipoma arising from perirenal tissue and acquired cystic disease-associated renal cell carcinoma: A rare case report

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.

Skull Base Collision Tumors: Giant Non-functioning Pituitary Adenoma and Olfactory Groove Meningioma

A collision tumor complex is composed of at least two different tumors, benign or malignant, with at least two different histopathological features located adjacent to each other in the exact anatomical localization. Pathologies such as meningiomas, pituitary adenomas, gliomas, and schwannomas may be involved in a collision tumor complex. However, co-occurrence of pituitary adenomas and meningiomas as skull base collision tumors is rare. Here, we present a 65-year-old male patient who presented with olfactory groove meningioma and non-functioning pituitary adenoma as a collision tumor. The patient was admitted with a headache and right-sided vision loss. The patient's first neurologic examination was consistent with temporal anopsia in the right eye. Subsequent contrast-enhanced cranial MRI revealed a 65x55x40 mm heterogeneously contrast-enhanced lesion in the anterior skull base extending from the sellar region to the corpus callosum. Because of the tumor size, a two-staged operation was planned. First, the tumor was partially excised via a right frontal craniotomy with a transcranial approach, and the tumor in the sellar region was left as a residue. The pathology reports after the first surgery showed pituitary adenoma and meningeal epithelial type meningioma (WHO Grade I). The residual tumor tissue was resected seven months later via an endoscopic endonasal approach, except for the part that invaded the right anterior cerebral artery. The optic nerve was decompressed. The patient was then referred to the radiation oncology clinic for radiosurgery. Collision tumors should be considered in the differential diagnosis in preoperative evaluation and surgical planning when heterogeneously contrast-enhanced areas significantly localized adjacent to each other are seen on cranial MRI. On the other hand, when the surgeon encounters sudden changes in the appearance or consistency of the tumor during the surgery, they should suspect these tumor complexes. The diagnosis of collision tumors is quite challenging but is of great importance regarding the patient's need for postoperative radiation therapy or the recurrence characteristics of tumors. However, more studies are needed on these complexes' etiology, surgical planning, and postoperative management.

Uterine collision tumor (PEComa and endometrioid carcinoma) in a tuberous sclerosis patient: a case report

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, co-expressing 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 a moderately 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.

Appendiceal collision tumors: case reports, management and literature review

Appendiceal tumors are incidentally detected in 0.5% cases of appendectomy for acute appendicitis and occur in approximately 1% of all appendectomies. Here, we report two cases of appendiceal collision tumors in two asymptomatic women. In both cases, imaging revealed right-lower-quadrant abdominal masses, which were laparoscopically resected. In both cases, histological examinations revealed an appendiceal collision tumor comprising a low-grade appendiceal mucinous neoplasm and well-differentiated neuroendocrine neoplasm (NEN). For complete oncological control, right hemicolectomy was performed in one patient for the aggressive behavior of NEN; however, histology revealed no metastasis. The other patient only underwent appendectomy. No further treatment was recommended. According to the latest guidelines, exact pathology needs to be defined. Proper management indicated by a multidisciplinary team is fundamental.

A Collision Tumor of Pit-1/SF-1-positive Double Pituitary Adenoma and a Craniopharyngioma Coexisting with Graves' Disease

Double or multiple pituitary adenomas expressing different types of transcription factors and collision tumors of pituitary adenomas and craniopharyngiomas are rare. In this report, we present a case of pituitary adenoma of two different cell populations, Pit-1 and SF-1, and an adenoma and craniopharyngioma collision tumor with coexisting Graves' disease. The patient had a 16-mm pituitary tumor with pituitary stalk calcification and optic chiasm compression but no visual dysfunction. Based on hormonal profile results, the tumor in the sella was considered a nonfunctioning pituitary adenoma; nevertheless, the pituitary stalk was invaded by a different lesion, which was later confirmed to be a craniopharyngioma. Using an endoscopic endonasal approach, the pituitary adenoma was removed; however, a small remnant remained medial to the right cavernous sinus. Because the pituitary stalk lesion was isolated from the pituitary adenoma, it was preserved to maintain pituitary function. Three years after the initial surgery, the patient suffered from Graves' disease and was treated with antithyroid medications. However, the intrasellar residual and pituitary stalk lesions gradually increased in size. A second surgery was performed, and the residual intrasellar and stalk lesions were completely removed. As per the initial and second histopathologies, the pituitary adenoma comprised different cell groups positive for thyroid-(TSH) and follicle-stimulating hormones, and each cell group was positive for Pit-1 and SF-1. The pituitary stalk lesion was an adamantinomatous craniopharyngioma. We believe that TSH-producing adenoma was involved in the development of Graves' disease or that treatment for Graves' disease increased TSH-producing adenoma.

A novel IRF2BP2::CDX2 Gene fusion in digital intravascular myoepithelioma of soft tissue: An enigma!

Soft tissue myoepitheliomas (STM) are benign myoepithelial neoplasms (of nonsalivary gland origin) arising, most commonly within subcutaneous and deep soft tissues of the extremities and rarely within bones. To the best of our knowledge, the intravascular location of STM as well as the identification of a novel IRF2BP2::CDX2 fusion have not been previously reported. Herein, we report a case of spindle cell myoepithelioma arising within the intravascular space of the right index finger in a 52-year-old male of more than 20 years duration. Histopathology demonstrated an intravascular tumefactive lesion composed of predominantly plump banal spindle cells in a fascicular arrangement within a mixed collagenous and chondromyxoid stroma colliding with papillary endothelial hyperplasia (Masson tumor). By immunohistochemistry, the lesional cells were positive for keratin-AE1/3, epithelial membrane antigen, S100, SOX10, glial fibrillary acid protein, calponin and negative for CD34, smooth muscle actin, desmin, p63, and ERG. Fluorescence in situ hybridization for EWSR1 gene rearrangement was negative. Next-generation sequencing detected a novel IRF2BP2::CDX2 fusion involving Exon 1 of the IRF2BP2 gene and Exon 2 of the CDX2 gene confirmed by reverse transcriptase polymerase chain reaction and Sanger sequencing. Further, clinical evaluation for a salivary gland mass in the head and neck region and magnetic resonance imaging (MRI) of the chest, abdomen, and pelvis was performed with no evidence of tumor elsewhere. Taken together, the overall features were considered diagnostic of STM. Our current case underscores the novelty of the IRF2BP2::CDX2 gene fusion in STM and its exceptionally rare intravascular location.

A unique case of anaplastic thyroid carcinoma comprising of two distinct patterns osteoclastic variant and squamous cell carcinoma in separate lobe imitating collision tumor: A case report

Anaplastic thyroid carcinoma with two distinct morphologies in two lobes with no intermixing is very rare and not reported earlier. Furthermore, osteoclastic variant of anaplastic thyroid carcinoma as well as primary squamous cell carcinoma without any differentiated components are also very rare with only few reported cases describing their cytological features. Herein, we are reporting a unique and first case of anaplastic thyroid carcinoma comprising of two distinct patterns osteoclastic variant and squamous cell carcinoma in different lobes in a 55-years-old lady with review of literature.

Secondary Sinonasal Collision Tumor of Papillary Squamous Cell Carcinoma and Small Cell Neuroendocrine Carcinoma After Nasopharyngeal Carcinoma Radiotherapy: A Case Report and Literature Review of Sinonasal Collision Carcinomas

In the head and neck region, small cell neuroendocrine carcinoma (SmNEC) is extraordinary infrequent. Collision malignancy is also a rare entity in the nasal cavity, with merely sporadic 6 case reports on primary collision tumor associated with neuroendocrine carcinoma. The development of a secondary SmNEC within the previous radiation field had uncommonly been described, and there was no report on secondary sinonasal collision carcinoma with SmNEC component as a side reaction of nasopharyngeal carcinoma (NPC) radiotherapy. In light of the rarity of these neoplasms, we presented a case of a sinonasal collision carcinoma of papillary squamous cell carcinoma (PSCC) and SmNEC after NPC radiotherapy. To our knowledge, it may be the first case of a secondary coexistence of two malignancies synchronously in the nasal cavity after NPC treatment. Recognizing this peculiar kind of collision tumor associated SmNEC could promote our understanding of this entity and hence propose optimal treatment strategies.

Case report: Highly differentiated endometrial adenocarcinoma that collided with uterine cervical carcinosarcoma

Uterine collision tumor is a rare pathological type composed of two or more malignant tumors. The components of these malignant tumors do not have histological mixing and are separated by the normal mesenchyme. Collision cancer is very rare, with uterine collision tumors being even rarer. Only a few cases have been reported in relation to uterine collision tumors. At present, there is no standard treatment guideline for uterine collision tumors, and a comprehensive treatment composed of surgery, radiotherapy, and chemotherapy is suggested. In this study, we report a 54-year-old female patient diagnosed with highly differentiated endometrial adenocarcinoma with cervical carcinosarcoma. The endometrial adenocarcinoma component invaded the deep myometrium (> 1/2 layer), involving the cervical glands and interstitium. The regional lymph node metastasis from endometrial adenocarcinoma was also detected. The patient underwent "transabdominal tumor cytoreduction (total hysterectomy + right adnexal resection + greater omentectomy + pelvic lymph node dissection + para-aortic lymph node dissection) + pelvic adhesion release." In addition, she has completed adjuvant radiotherapy and chemotherapy. After reviewing previous reports of collision tumors in different positions of the uterus, we found that collision tumors between the cervix and uterine body are very uncommon. In addition, we have not found any reports on the metastasis of sarcoid components, no matter what the composition is.

Thyroid Collision Tumors: The Presence of the Medullary Thyroid Carcinoma Component Negatively Influences the Prognosis

Thyroid collision tumors (TCTs) are rare pathological findings, representing <1% of thyroid cancers. This study aimed to compare the main pathological features of TCTs containing medullary thyroid carcinoma (MTC) and papillary thyroid carcinoma (PTC) components with MTC-only tumors and PTC-only tumors. Methods: The retrospective study included 69 cases diagnosed with TCTs (with simultaneous MTC and PTC components), MTC and PTC. All tumors were comparatively assessed for the classical histopathological prognostic features, including a new grading system for MTC. Results: The main component of TCTs had more frequent microscopic extrathyroidal extension (mETE) (p = 0.000), lymphovascular invasion (LVI) (p = 0.000), perineural invasion (PNI) (p = 0.044), and lymph node metastasis (p = 0.042). Additionally, the TCTs’ MTC component presented with more frequent LVI (p = 0.010). Comparing TCTs’ MTC and PTC components with MTC-only tumors and PTC-only tumors revealed that only the TCTs’ MTC components had statistically significant more frequent mETE (p = 0.010) than MTC-only tumors. When applied to the MTC component of TCTs, the pathological parameters of the new grading system of MTC showed no correlations with other microscopic or clinical aspects. Conclusion: Using classical pathological prognostic features, the comparative analysis revealed that the main TCTs’ component was more aggressive than the minor one. Contrary to PTCs, in TCTs, the medullary component was more aggressive than the papillary one, but also more aggressive than MTC-only tumors.

Collision tumor of the appendix incidentally discovered in a patient diagnosed with an adenocarcinoma of the colon: a case report

Collision tumor of the appendix is an extremely rare entity, defined as the coexistence of two independent tumors located in the same site without transitional changes. We describe in this report the case of a 75-year-old man who presented with an acute abdominal pain, nausea and vomiting. Physical examination revealed an abdominal distension with a hypogastric mass. Abdominal computed tomography showed colonic obstruction related to a sigmoid tumor. Therefore, a total colectomy was made. Macroscopic specimen examination showed a sigmoid tumor associated to a cystic dilatation of the appendix tip with mucoid content. Histological examination of the appendix showed the co-existence of two independent tumors located in the tip, without transitional changes: pTis low-grade appendiceal mucinous neoplasia and grade 1 neuroendocrine tumor. The latter was discovered incidentally during histological examination. We draw attention through our presentation to the importance of a thorough macroscopic and histological examination of the appendix.

Collision tumor of the thyroid - a challenge during the COVID-19 pandemic

Some of the patients with anaplastic thyroid carcinomas have a coexistent differentiated thyroid cancer, sustaining the hypothesis that this cancer may develop from more differentiated tumors. We describe a case with a collision tumor of the thyroid, defined as a neoplastic lesion composed of two distinct cell populations, with distinct borders. The patient presented during the COVID-19 pandemic with dysphonia, dyspnea, multinodular goiter and a painless, rapidly enlarging, left cervical swelling. She had been first time diagnosed with left nodular goiter in 2007, with an indication for surgery, which she declined. After partial excision of the left latero-cervical adenopathy, the pathological analysis showed massive lymph node metastasis from anaplastic thyroid cancer. A total thyroidectomy was done; the postoperative pathological exam identified a papillary thyroid microcarcinoma in the right lobe and an anaplastic thyroid cancer in the left lobe. Postoperatively, levothyroxine treatment was started and the patient was referred to radiotherapy. This case highlights the importance of urgent management of some cases with compressive multinodular goiter, even during the COVID-19 pandemic.

Collision of Two Tumors: A Case Report of a Lung Adenocarcinoma With Metastasis to a Pituitary Adenoma

A collision tumor involving metastasis to a pituitary adenoma is rare. We describe a case of a 68-year-old Bidayuh woman with underlying treatment-responsive lung adenocarcinoma, who presented with mass effect, panhypopituitarism and polyuria. Her initial imaging study reported pituitary macroadenoma, and she was treated with hormone replacement therapy. She then underwent transsphenoidal tumor debulking surgery with subsequent histopathological findings of a collision tumor of an adenocarcinoma with metastasis to a non-functioning pituitary adenoma.

Uterine collision tumor of endometrial stromal sarcoma and endometrioid adenocarcinoma: A rare case report and review of literature

Collision tumors are characterized by occurrence of two or more histologically distinct tumor types at the same anatomic site. Collision tumors have been reported in various organs, such as esophagus, stomach, colon, kidney, lung, skin, thyroid, breast, ovary and uterus. Uterine collision tumors of epithelial and mesenchymal origin are rare and often underrecognized. We report a rare concurrent occurrence of endometrial stromal sarcoma and endometrioid adenocarcinoma in a 65-year-old female. It is important to differentiate collision tumors from carcinosarcoma due to impact on clinical management and prognosis. Extensive gross sampling and careful morphological examination aided by immunohistochemical studies is necessary for the diagnosis of this rare entity. This case report aims to increase the awareness of this rare pathological entity with discussion on the management issue based on review of literature. This is the first case in Indian literature to the best of our knowledge.

The Appendix: A Rare Case of an Appendiceal Collision Tumor

Appendicitis is a common cause of right lower quadrant pain. However, appropriate diagnostic evaluation and a high clinical suspicion can reveal alternative etiologies that are not so commonly encountered. In this report, we present a rare case of an appendiceal collision tumor involving two distinct neoplasms as the source of the patient's pain and describe how thoughtful clinical maneuvering led to its diagnosis and treatment.

Invasive ductal carcinoma and small lymphocytic lymphoma/chronic lymphocytic leukemia manifesting as a collision breast tumor: A case report and literature review

Collision breast tumors, consisting of breast cancer (BC) and non-Hodgkin’s lymphoma (NHL), are extremely rare. Here we report the case of a 64-year-old woman with a collision tumor in her left breast mass that was composed of invasive ductal carcinoma and small lymphocytic lymphoma/chronic lymphocytic leukemia. In addition, we reviewed the published comparable English-language literature. Collision breast tumor composed of BC and NHL is extremely rare. For that reason, there is a lack of consensus about the underlying mechanism, and diagnosing it without delay remains a complex clinical challenge. We found that post-menopausal, age-related estrogen levels changes and Epstein-Barr virus infection are possible pathogenic factors. However, the symptoms are almost identical, and it is difficult to distinguish a simple breast tumor from a breast collision tumor. In this study, we reviewed the clinical features of all patients with BC and NHL colliding breast tumors; this information might enable early identification and prevention of misdiagnosis.

Clinically unsuspected primary hepatic mucosa-associated lymphoid tissue lymphoma collision with an intrahepatic cholangiocarcinoma: A case report and literature review

A synchronous tumor represents two histologically distinct neoplasms occurring at the same anatomic site, each displaying a distinct tumorigenesis pathway; they can be primary, secondary, or a mixture. The occurrence of an adenocarcinoma and lymphoma has been reported in gastrointestinal and pulmonary sites; however, such a finding in hepatobiliary system remains elusive. Primary hepatic lymphoma is rare, while primary biliary mucosa-associated lymphoid tissue lymphoma is an even rarer event; hence, its collision with an intrahepatic cholangiocarcinoma could be entirely missed both in practice and in the literature. We herein reported a case of biliary mucosa-associated lymphoid tissue lymphoma occurring synchronously with an intrahepatic cholangiocarcinoma in a 78-year-old female following a biopsy-proven intrahepatic cholangiocarcinoma and hepatectomy. Microscopic examination identified atypical lymphoid population intermingled with this intrahepatic cholangiocarcinoma. An immunohistochemical panel uncovered an incidental mucosa-associated lymphoid tissue lymphoma occurring with this intrahepatic cholangiocarcinoma. This clinically missed entity led to comprehensive systemic investigation/staging, with subsequent detection of bone marrow involvement by stage IV lymphoma. This unique case highlights the importance of astute histomorphological evaluation and thorough ancillary studies in identifying a clinically unsuspected neoplasm in close contact with a known tumor.

A collision tumor of solitary fibrous tumor/hemangiopericytoma and meningioma: A case report with literature review

An intracranial collision tumor is a rare lesion composed of two histologically different neoplasms in the same anatomic location. Even more rare is the collision tumor of a solitary fibrous tumor/hemangiopericytoma (SFT/HPC) and meningioma. The patient was a 46-year-old woman who had a 40 × 35 × 30-mm mass in the vermis of the cerebellum. Histologically, the mass consisted of two different components. One component showed the morphology of meningioma (World Health Organization (WHO) grade I), and the other component exhibited small round cell proliferation with hypercellular density, which was revealed to be SFT/HPC (WHO grade III) based on STAT6 immunohistochemistry. STAT6 showed completely different immunohistochemistry results in these two components (nuclear-negative in meningioma and nuclear-positive in SFT/HPC). Since these two neoplasms are associated with different prognoses, they should be distinguished from each other. When meningioma and an SFT/HPC-like lesion are identified morphologically, it is important to recognize the presence of such a collision tumor composed of meningioma and SFT/HPC, and identify the SFT/HPC component by employing STAT6 immunohistochemistry.

A Wolf in Sheep's Clothing: Collision of Melanoma and Keratoacanthoma

Collision tumors consisting of melanoma and squamous cell carcinoma are very rare. We present the case of a deceptive hyperkeratotic nodule on the forearm of a 72-year-old woman, which clinically appeared to be a squamous cell carcinoma, keratoacanthoma type. Histological examination surprisingly revealed a coexisting epithelioid melanoma. Thus, this case report shows the importance of an early histopathological and immunohistochemical workup to prevent unnecessary diagnostic and therapeutic delay with negative effects on prognosis.

A Rare Collision Tumor: Adenocarcinoma in the Ampulla of Vater and Neuroendocrine Tumor in the Lower Part of the Common Bile Duct

In the biliary tree, only three cases of neuroendocrine tumor (NET) synchronous with adenocarcinoma have been reported so far. We experienced a case of NET, grade 2 (G2), of the common bile duct associated with adenocarcinoma of the ampulla of Vater (AoV). A Japanese man at his 60’s visited a local doctor, and obstructive jaundice was pointed out. Under the clinical diagnosis of carcinoma of the AoV, 20 x 20 mm, T3aN0M0 stage IIB, pylorus-preserving pancreaticoduodenectomy was performed. Dynamic computed tomography in an artery-dominant phase and microscopic examination revealed that the mass consisted of two different components; hypovascular, 2.5 cm-sized, exophytic adenocarcinoma in the AoV and hypervascular, 1.5 cm-sized, polypoid NET (G2) in the lower part of the common bile duct. The NET diffusely expressed neuroendocrine markers, including somatostatin receptor-2 (SSTR2), and adenocarcinoma cells arising from tubular adenoma focally expressed the neuroendocrine markers. Both malignancies were positive for caudal-type homeobox-2 (CDX2). It is presumed that NET occurred from intestinal-type adenoma/adenocarcinoma.

Metastatic Thyroid Osteosarcoma With Concomitant Multifocal Papillary Carcinoma Presenting as a Collision Tumor

Metastatic involvement of the thyroid occurs rarely, by either hematogenous spread or direct extension from adjacent organs. The most frequent metastatic tumors are clear cell, renal cell, lung, breast, and squamous cell carcinoma.

The occurrence of osteosarcoma and papillary thyroid carcinoma in the same patient is rare, with only a few reported cases in the literature. On the other hand, only one case of osteosarcoma thyroid metastasis has so far been reported.

We herewith present another case with metastatic osteosarcoma and multifocal papillary thyroid carcinoma presenting as a collision tumor and review the relevant literature.

Next-generation sequencing reveals novel mutations in a collision tumor of glioblastoma and meningioma

Primary intracranial collision tumors are rare in patients without predisposing factors. We report such a case in a 42-year-old female who presented with headaches and altered mental status. Imaging revealed a single heterogeneous, rim-enhancing lesion in the left parieto-occipital periventricular region, involving the corpus callosum. Stereotactic biopsy demonstrated glioblastoma. Subsequent tumor resection showed histologic evidence of glioblastoma and meningioma. Next-generation sequencing was performed on both tumor components. The glioblastoma exhibited a CDKN2A homozygous deletion and novel missense mutations in TAF1L and CSMD3, while no definitive genetic alterations were identified in the meningioma. Next-generation sequencing may yield insight into molecular drivers of intracranial collision tumors and aid in identifying future therapeutic targets.

Next-generation sequencing (NGS) reveals novel mutations in a collision tumor of GBM and meningioma. NGS has the potential to yield insight into molecular drivers of intracranial tumors and identify therapeutic targets.

Collision tumor of sebaceous carcinoma and squamous cell carcinoma of the eyelid: Case report

BACKGROUND

Collision tumors are rare clinical entities that two heterogeneous neoplasms are concurrently adjacent to each other at the same location. The association of a squamous cell carcinoma and a malignant adnexal tumor is even infrequent.

CASE PRESENTATION

The case of a 79-year-old woman having a slow-growing and painless tumor on the left lower eyelid was presented. The lesion, about 15 mm in diameter, was nodular, irregular, and yellow-discolored. Histopathologic and immunohistochemical findings disclosed concurrence of sebaceous carcinoma as well as squamous cell carcinoma in one specimen. Wide excision of the tumor with frozen section control and eyelid reconstruction were performed. Oncologic survey revealed no other lesion. At 6-month follow-up, no evidence of recurrence or metastasis was presented.

CONCLUSION

Collision tumor composed of sebaceous carcinoma and squamous cell carcinoma in eyelid may be the first case described in the literature. For increasing accuracy of diagnosis and management, a thorough clinical examination and detailed histopathologic analysis, along with multidisciplinary discussion, are prerequisites.

High-grade Urothelial Carcinoma with Malignant Melanocytic Differentiation

Urothelial carcinoma usually shows divergent differentiation and variant histology with squamous and glandular morphology being most common. In this report, we present a case of divergent malignant melanocytic differentiation in a high-grade urothelial carcinoma. A 98-year-old East Asian woman with an anterior bladder wall mass underwent resection, which revealed a high-grade poorly differentiated tumor. A minor component of high-grade papillary urothelial carcinoma and carcinoma in situ is also present. The majority of the tumor cells are morphologically and immunohistochemically consistent with melanoma, a minority of cells are positive for urothelial markers, and rare cells coexpress both melanocytic and urothelial markers. Cells that express melanocytic markers or urothelial markers are intimately admixed together. Taken together, a diagnosis of high-grade urothelial carcinoma with malignant melanocytic differentiation was rendered. This is the first report in the literature of malignant melanocytic differentiation in a high-grade urothelial carcinoma, a finding that may have important diagnostic and therapeutic implications.

Collision kidney tumor with clear cell renal cell carcinoma and papillary type 1 renal cell carcinoma. A case report and review of the literature

INTRODUCTION

The most common renal neoplasms include clear cell, papillary, and chromophobe renal cell carcinomas. The simultaneous occurrence of different histological types of adjacent neoplasms in the same organ is known as a collision tumor. Collision kidney tumors have already been described but only in rare cases.

CASE DESCRIPTION

In this case report we present a 68-year-old man with chronic kidney insufficiency under dialysis who underwent an open right nephrectomy in our department with the histological diagnosis of a collision kidney tumor consisting of clear cell and papillary type 1 renal cell carcinoma.

CONCLUSION

To the best of our knowledge, our case of a collision kidney tumor consisting of clear cell RCC and papillary type 1 RCC, is unique in literature.

Tiny but Mighty: Collision Tumor of a Superficial Adenocarcinoma Arising From a Tubulovillous Adenoma with Associated Low-Grade Follicular Lymphoma

Collision tumors are rare and there have only been a few previously described cases between an intestinal adenoma and a lymphoma. We report the first case of a 74-year-old woman who on investigation for iron deficiency had a tubulovillous adenoma with underlying follicular lymphoma. The atypical lymphoid proliferation showed immunohistochemical positivity for cluster of differentiation 20 (CD20), B-cell lymphoma 2 (BCL2), and B-cell lymphoma 6 (BCL6). Subsequent right hemicolectomy showed a superficially invasive adenocarcinoma.

Collision Tumors of Gastric Adenocarcinoma and Mucosa-associated Lymphoid Tissue Lymphoma

A 65-year-old woman with a history of treatment for splenic marginal zone B-cell lymphoma and gastric mucosa-associated lymphoid tissue (MALT) lymphoma underwent esophagogastroduodenoscopy. A reddish elevated lesion was found in the fundus of the stomach. On image-enhanced endoscopy, several findings, such as glandular structures of varying sizes suggesting well-differentiated adenocarcinoma, pruned blood vessels, and dilated blood vessels in deeper mucosa suggesting MALT lymphoma, were observed. The final pathological diagnosis after surgical resection was collision tumors of well-differentiated adenocarcinoma and MALT lymphoma. The features of both tumors could be observed simultaneously with image-enhanced endoscopy.

A Collision between Cavernous-Capillary Hemangioma with Stromal Luteinization and Serous Cystadenoma

A collision tumor represents a coexistence of two adjacent but histologically distinct tumors without histologic admixture in an organ. Serous tumors of the ovary are the most common forms of epithelial tumors, and cavernous hemangiomas are rare in the ovary. Howev-er, a collision between them is an extremely rare pathology. Here the author presents a report of a 74-year-old woman whose ultrasound examines establishes rounded left ovary formation with hypo- and hyperdense sections. Paraclinical: CA125 within normal range. Serum levels free testosterone 3.79 nmol/l (normal 0.49-2.64 nmol/l for women). The histology showed benign serous cystadenoma and vascular lesions composed of capillary and cavernous vessels amongst luteinized stromal cells. The luteinized cells were positive for inhibin A. The endothelial cells were negative for estrogen and progesterone receptor. A search was conducted in the Medline database via PubMed using the terms: 'hemangioma', 'ovary', 'collision', 'serous cystadenoma', no more than 70 articles for ovarian hemangiomas appeared, and no articles for a collision between serous cystadenoma and mixed hemangioma with stromal luteinization in the ovary. From the reference, this is the first reported case of collision between serous cystadenoma and mixed cavernous-capillary hemangioma with stromal luteinization in the ovary. This rare case of collision between tumors in the ovary sheds light on possible tumor pathology in the woman's reproductive system, which must be considered by gynaecologists and pathologists.

Intravascular Large B-Cell Lymphoma and Renal Clear Cell Carcinoma as Collision Tumor: A Case Report and Review of the Literature

Intravascular large B-cell lymphoma (IVLBCL) is a rare type of extranodal large B-cell lymphoma characterized by the selective growth of lymphoma cells within the lumina of vessels. The patient usually presents with nonspecific symptoms and a remarkable deterioration in performance status. The occurrence of synchronous IVLBCL and renal cell carcinoma (RCC) is extremely rare. A right kidney tumor was found in a 72-year-old man with a history of low back pain. The kidney was enlarged, with a tumor mass measuring 4.5 × 4 × 4 cm. Sections exhibited a RCC (clear cell type, nuclear grade I). Also an extensive tumor affecting capillaries and small veins was present, positive for CD45, CD20, BCL-2, and MUM1/IRF-4, consistent with IVLBCL. The lymphoma was circumscribed to the RCC. The final diagnosis was IVLBCL with a RCC as collision tumor. After that, with neurological findings, central nervous system compromise by lymphoma was made. The patient started a first cycle of chemotherapy, progressive deterioration of the sensorium, and positive blood cultures for Klebsiella pneumoniae and Escherichia coli. The patient died 8 days later of acute respiratory failure. No autopsy was done. IVLBCL is an aggressive and systemic disease characterized by massive proliferation of tumor cells without a known primary site. Clinical identification and histopathologic diagnosis are relevant issues in the therapeutic management of these lymphomas. Until now, only one case of IVLBCL coexisting with RCC has been reported. In this article, we report a second case of IVLBCL with RCC simultaneous, as an unusual collision tumor.

Coexistence of craniopharyngioma and meningioma: Two rare cases and literature review

Most of the craniopharyngioma is considered to derive from residual epithelial cells during the craniopharyngeal canal degeneration. Meningioma accounting for the primary intracranial neoplasm is considered to be mainly derived from cells of arachnoid granulations. Nevertheless, rare cases show coexistence of craniopharyngioma and meningioma.Case 1: A 43-year-old male patient referred to the hospital due to paroxysmal headache combined with blurred vision for 1 month. On physical examination, the visual acuity of left eye was poorer than that of the right eye. The visual acuity of the right eye near the nasal part showed defect.MRI and pathological examination were performed. The patient received intracranial tumor resection. After surgery, the patient showed hormone disorder, followed by corresponding treatment. However, the patient was lost in the 6-month follow-up.Case 2: The 64-year-old male patient presented to our department due to decline of visual acuity within 1 year combined with polydipsia (5,000 ml per day), polyuria and fatigue for 6 months. On physical examination, the bilateral visual acuity showed decline, especially the temporal part which was nearly hemiscotosis. MRI was performed. The adamantinomatous craniopharyngioma was diagnosed with the HE staining findings. The patient received intracranial resection. After surgery, the patient was in a deep coma condition, and was lost in the follow-up.In this case study, we presented 2 patients with coexistence of craniopharyngioma and meningioma. In addition, a complete literature review was carried out to illustrate the studies on coexistence of craniopharyngioma and meningioma. Meanwhile, we tried to explain the possible mechanisms for such condition.

Spindle cell melanoma coexisting with chronic lymphocytic leukemia/small lymphocytic lymphoma: a rare collision tumor in multiple sites

A strong association has been reported between chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) and malignant melanoma (MM). In rare cases of MM, lymphoid malignancies may be detected incidentally during sentinel lymph node biopsies. In this case, we found a unique collision of MM and CLL infiltration in the skin. An 88-year-old male patient presented with a mass on the nasal root. Histopathological examination of the skin biopsy specimen revealed a deeply infiltrative, atypical spindle cell proliferation in the background of a collagenous stroma. Accompanying this lesion, there were foci of monotonous lymphoid cell populations involving skin appendages. In the immunohistochemical studies, the spindle cells were diffusely positive for S100, and focally positive for Melan-A and HMB45; the lymphoid cells were positive for CD20, CD5, and Bcl-2 and negative for CD3, Bcl-6, CD10, and Cyclin D1. Histopathological and immunohistochemical findings were consistent with diagnoses of spindle cell melanoma and CLL. Interestingly, these two tumors together in their same morphological appearance were confirmed in a subsequent liver biopsy. Active skin surveillance of patients with CLL may be important to detect MM at an early stage that correlates with a better prognosis.

Collision tumors: A review of their types, pathogenesis, and diagnostic challenges

A collision tumor is a neoplastic lesion comprised of two or more distinct cell populations that maintain distinct borders. Collision tumors, which are rare but well documented, can be composed of two benign tumors, a benign and malignant tumor, and two malignant tumors. Although case reports and reviews on specific types of collision tumors exist, a cohesive source discussing these tumors is lacking. We critically reviewed the literature by analyzing case reports and retrospective studies in order to evaluate the following regarding collision tumors: definitions, types, pathogenesis, diagnosis, and management. Reports of these tumors are infrequent but not insignificant, and accurate classification and diagnosis will lead to better patient outcomes.

Triple negative lobular breast carcinoma metastatic to an ovarian fibrothecoma

A postmenopausal woman with lobular breast carcinoma metastatic to a large ovarian fibrothecoma is presented. The two metastatic tumor nodules were grossly subtle and could have been overlooked in the background of the large ovarian stromal tumor. Thorough sampling of the tumor for histologic examination and supporting immunohistochemical stains were important in establishing the diagnosis. Differential diagnostic considerations are discussed.

Primary Hepatic Carcinosarcoma Composed of Hepatocellular Carcinoma, Cholangiocarcinoma, Osteosarcoma and Rhabdomyosarcoma With Poor Prognosis

BACKGROUND

Primary hepatic carcinosarcoma is a rare subtype of liver malignancy, with only a small number of cases described in the English literature.

CASE REPORT

We report the case of a 72-year-old man with a history of hepatitis C, who presented with complaints of abdominal pain. The patient's alpha fetoprotein (AFP) level was highly elevated at 7,406 ng/ml. His albumin, total bilirubin, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase levels were within normal ranges. Computer tomographic scans discovered a 12×9×8 cm mass in the left lobe of the liver, extending to the anterior gastric wall. A partial hepatectomy of segments 2 and 3 with en bloc distal gastrectomy and omentectomy, a Roux-en-Y gastrojejunostomy, and a cholecystectomy were performed. Pathology revealed the mass to be a hepatic carcinosarcoma composed of collision tumor of four malignant components: hepatocellular carcinoma, cholangiocarcinoma, osteosarcoma and rhabdomyosarcoma. One and half month post-surgery, the patient was found to have a mass confirmed by biopsy as hepatocellular carcinoma in the right lobe, nodules in his lung and bone, and his AFP level elevated to 51,027.6 ng/ml. He died after two months during hospice care.

CONCLUSION

To the best of our knowledge, this is the first documented case of primary hepatic carcinosarcoma with collision tumor of four malignant entities (hepatocellular carcinoma, cholangiocarcinoma, osteosarcoma and rhabdomyosarcoma). The pathogenesis, diagnosis, treatment and prognosis of this disease are discussed.

Collision tumor of meningioma and metastatic renal clear cell carcinoma: a case report

Distinct tumors in direct contact with one another are known as collision tumors and collision tumors of meningioma and metastatic renal cell carcinoma have not been previously reported. We report a 71-year-old female with a history of renal cell carcinoma who was presented with slow response and gait imbalance for 4 months. Brain MRI showed a mass in the base of right middle cranial fossa. The mass was completely removed. Histopathologic and radiographic findings provided evidence for a collision composed of meningioma and metastatic renal clear cell carcinoma.

Coexistence of Two Different Thyroid Malignancies: A Collision Phenomenon

The term “collision tumor” is described as the coexistence of two or more histologically distinct neoplastic morphologies separated by normal tissue in the same organ. Simultaneous papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC) of the same thyroid lobe is a very rare pathology. Herein, we report a case of PTC and FTC of the same thyroid lobe. A 79-year-old man was evaluated at our hospital for the presence of left hip pain of two-month duration after sustaining a physical trauma to the left side of his body three days prior to admission. X-ray imaging of the left femur revealed a large lytic bony lesion at the proximal end of left femur. Biopsy of the bone lesion was suggestive of FTC. Computed tomography (CT) of the neck revealed an enlarged thyroid with a cystic lesion in the left lobe of the thyroid gland. Total thyroidectomy was performed. Histopathology revealed two separate primary malignancies of PTC and FTC. Genetic studies for RAS gene mutation were negative. He was initiated on suppressive doses of levothyroxine following thyroidectomy. Three months after surgery, thyrotropin alfa stimulated 204.5 mCi I-131 was administered. At seven months of follow-up, the thyroglobulin level was in the lower end of the normal range and anti-thyroglobulin antibody (anti Tg) remained negative (< 1.0 IU/mL). He was doing well and reported no symptoms.

For each type of well-differentiated thyroid cancers, several genes have been identified. However, thus far, no specific gene mutation responsible for the pathogenesis of the different tumor types has been described. Management of thyroid collision tumor is usually complex due to the presence of different pathology in the tumor tissues and given the fact that literature on this condition is limited. Typically, the treatment needs to be individualized. Our report brings up a concept that the occurrence is a rare phenomenon of simultaneous mutation of different genes that could give rise to different thyroidal neoplasms.

Squamous Cell and Adenoid Cystic Carcinoma Collision Tumor of the Soft Palate Treated with Surface Mold Brachytherapy

Simultaneous primary cancers are rare in the oropharynx. This report describes the first reported case of a collision tumor of squamous cell and adenoid cystic carcinoma in the soft palate. The patient was immunosuppressed with a history of liver transplantation, smoking and heavy alcohol drinking. He was treated with wide local excision followed by adjuvant radiotherapy with surface acrylic mold brachytherapy. This technique was used instead of external beam radiotherapy in order to minimize toxicity. The patient tolerated the treatment well and with the only acute grade two mucositis at the soft palate and minimal late toxicity. There is no evidence of disease recurrence and the patient continues to maintain excellent quality of speech and swallowing 14 months after treatment completion.

Collision Tumor of Endometrial Large Cell Neuroendocrine Carcinoma and Low-Grade Endometrial Stromal Sarcoma: A Case Report and Review of the Literature

Large cell neuroendocrine carcinoma (LCNEC) of the endometrium is an exceedingly rare histologic subtype of endometrial cancer (0.8%). These tumors are highly aggressive with a propensity for metastasis and have a poor prognosis. Among the 17 cases reported to date, 9 cases were pure large cell neuroendocrine tumors and 8 were collision tumors of LCNEC with endometrial carcinomas (7 endometrioid and 1 serous). In this article, we report a case of collision tumor composed of an endometrial LCNEC and a low-grade endometrial stromal sarcoma (LGESS). The patient was a 48 year-old woman who presented with a large abdominal mass for about 10 years and underwent total hysterectomy, bilateral salpingo-oophorectomy, and tumor debulking. Microscopic evaluation demonstrated an LGESS with extensive osseous metaplasia that penetrated through the myometrium and invaded into pelvic and abdominal cavity, forming a 40.0-cm mass. Cytogenetic analysis of the LGESS revealed an abnormal female karyotype (45, XX) with multiple structural abnormalities. Incidentally, small foci of LCNEC were identified within the endometrium. The LCNEC focally invaded the myometrium with involvement of the endocervix, extensive lymph-vascular space invasion, and metastases to bilateral ovaries. Subsequently, the patient was treated with cisplatin/etoposide chemotherapy and had been doing well for about a year until presenting with recurrence of LCNEC in the abdomen. She passed away a month later due to medical complications. This report reveals an extremely rare endometrial collision tumor with unusual pathologic features and clinical presentations.

A Collision between Fibroma and Serous Ovarian Cystadenoma Mimicking Carcinoma

Collision tumors represent a coexistence of two adjacent but histologically distinct tumors without histologic admixture in an organ.

Ovarian fibroma is the most common benign stromal tumor. Serous tumors of the ovary are the most common of epithelial tumors. However, a collision between them is a rare pathology mimicking a malignant tumor. We report a 63-year-old woman with sparse postmenopausal bleeding. Ultrasound examination of organs in a small pelvis rounded right ovary formation with hypo and hyperdense sections. Paraclinical: CA125 slightly increased. Histological: collision between two benign ovarian tumors imitating carcinoma.