An Intrahepatic Cholangiocarcinoma with Focal Rhabdoid Features and SMARCA4-Deficiency

Intrahepatic cholangiocarcinoma with rhabdoid morphology is rare, and only three case reports have been published to date, none of which discuss the genetic changes in the rhabdoid component. We present a case of intrahepatic cholangiocarcinoma with focal rhabdoid features and SMARCA4-deficiency detected using immunohistochemistry. A Japanese man in his 60s without viral hepatitis was diagnosed with an avascular tumor in the liver, measuring 4.4 cm in the greatest dimension. The tumor was mostly composed of moderately differentiated adenocarcinoma, focal poorly differentiated adenocarcinoma, and an undifferentiated rhabdoid component. Immunohistochemical analysis showed an inclusion-like staining pattern for keratin AE1/AE3 and vimentin in the rhabdoid component. BRG1/SMARCA4 was detected in the differentiated component but not in the poorly- and undifferentiated components. Our novel findings reflecting the morphological and genetic heterogeneity of intrahepatic cholangiocarcinoma and will aid the research on drugs targeting the aberrant SWItch/Sucrose NonFermentable complex.

INI1-Intact Sinonasal Carcinoma with Rhabdoid Features

Sinonasal malignancies are known for their associated poor prognosis and diversity of histologic features. While poor prognosis is largely due to advanced disease at presentation, histologic features also play a significant role. Therefore, accurate pathologic diagnosis is of utmost importance. Here, we describe a 63-year-old male with chronic left-sided nasal obstruction and left-sided epistaxis who was found to have a large mass occupying most of the nasal cavity extending through the nasopharynx to just below the nasopharyngeal surface of the soft palate. During surgical excision, the mass was noted to originate from the floor of the maxillary sinus with erosion of the medial wall of the maxillary sinus. Pathology revealed a diagnosis of INI1-intact poorly differentiated composite carcinoma with rhabdoid phenotype and sarcomatoid and squamous cell carcinoma foci arising within an inverted papilloma. Included in this report is a detailed description of both the patient’s medical course and this pathologically novel sinonasal neoplasm. We aim to elucidate this rare tumor’s complex features in order to improve future diagnosis and stimulate prospective research on sinonasal malignancies with complex histology.

Pediatric meningioma with rhabdoid features developed at the site of skull fracture: illustrative case

BACKGROUND Pediatric meningiomas are rare, and only a few cases attributed to trauma and characterized by development at the site of bone fracture have been reported. Both pediatric and traumatic meningiomas have aggressive characteristics. OBSERVATIONS An 11-year-old boy who sustained a head injury resulting from a left frontal skull fracture 8 years previously experienced a convulsive attack. Imaging revealed a meningioma in the left frontal convexity. Total removal of the tumor with a hyperostotic section was successfully achieved. Intraoperative investigation showed tumor invasion into the adjacent frontal cortex. Histologically, the surgical specimen revealed a transitional meningioma with brain invasion and a small cluster of rhabdoid cells. This led to a final pathological diagnosis of an atypical meningioma with rhabdoid features. The postoperative course was uneventful, and no recurrence of the tumor was found after 2 years without adjuvant therapy. LESSONS This is the first report of a pediatric meningioma with rhabdoid features occurring at the site of a skull fracture. Meningiomas that contain rhabdoid cells without malignant features are not considered to be as aggressive as rhabdoid meningiomas. However, the clinical course must be carefully observed for possible long-term tumor recurrence.

Choroid Plexus Carcinoma with Rhabdoid Features: A Case Report

The case of a patient under 2 years of age with acute vomiting, fever and seizures. MR imaging of the brain revealed a right lateral intraventricular mass and mild hydrocephalus. Surgery achieved gross total tumor resection, but tumor histology revealed choroid plexus carcinoma with heavy stratification and atypical “rhabdoid” cells.

Germline BAP1 Mutation in a Family With Multi-Generational Meningioma With Rhabdoid Features: A Case Series and Literature Review

Meningioma is the most common primary brain tumor, and recurrence risk increases with increasing WHO Grade from I to III. Rhabdoid meningiomas are a subset of WHO Grade III tumors with rhabdoid cells, a high proliferation index, and other malignant features that follow an aggressive clinical course. Some meningiomas with rhabdoid features either only focally or without other malignant features are classified as lower grade yet still recur early. Recently, inactivating mutations in the tumor suppressor gene BAP1 have been associated with poorer prognosis in rhabdoid meningioma and meningioma with rhabdoid features, and germline mutations have been linked to a hereditary tumor predisposition syndrome (TPDS) predisposing patients primarily to melanoma and mesothelioma. We present the first report of a familial BAP1 inactivating mutation identified after multiple generations of a family presented with meningiomas with rhabdoid features instead of with previously described BAP1 loss-associated malignancies. A 24-year-old female presented with a Grade II meningioma with rhabdoid and papillary features treated with subtotal resection, adjuvant external beam radiation therapy, and salvage gamma knife radiosurgery six years later. Around that time, her mother presented with a meningioma with rhabdoid and papillary features managed with resection and adjuvant radiation therapy. Germline testing was positive for a pathogenic BAP1 mutation in both patients. Sequencing of both tumors demonstrated biallelic BAP1 inactivation via the combination of germline BAP1 mutation and either loss of heterozygosity or somatic mutation. No additional mutations implicated in oncogenesis were noted from either patient’s germline or tumor sequencing, suggesting that the inactivation of BAP1 was responsible for pathogenesis. These cases demonstrate the importance of routine BAP1 tumor testing in meningioma with rhabdoid features regardless of grade, germline testing for patients with BAP1 inactivated tumors, and tailored cancer screening in this population.

Rapidly fatal SMARCA4-deficient undifferentiated sarcoma originating from hybrid hemosiderotic fibrolipomatous tumor/pleomorphic hyalinizing angiectatic tumor of the foot

Pleomorphic hyalinizing angiectatic tumor (PHAT) of soft parts and hemosiderotic fibrolipomatous tumor (HFLT) are two rare low-grade locally recurring neoplasms with predilection for the foot/ankle. Recent studies support a close link between the two entities, and origin of PHAT from HFLT and occurrence of hybrid HFLT/PHAT have been documented. Both lesions often harbor TGFBR3 or MGEA5 rearrangements. Rare sarcomas originating from HFLT/PHAT have been reported, typically resembling myxofibrosarcoma or myxoinflammatory fibroblastic sarcoma. We describe a novel SMARCA4-deficient undifferentiated sarcoma with rhabdoid features originating from hybrid HFLT/PHAT in the foot of a 54-year-old male. The tumor pursued a highly aggressive course with rapid regrowth after resection and multiple metastases resulting in patient’s death within 5 months, despite systemic chemotherapy. Immunohistochemistry revealed SMARCA4 loss in the undifferentiated sarcoma, but not in the HFLT/PHAT. Molecular testing confirmed TGFBR3/MGEA5 rearrangements. This report expands the phenotypes of sarcomas developing from pre-existing PHAT/HFLT.