Background and Purpose Angiocentric glioma is a rare, World Health Organization grade I tumor that is seen predominantly in children and young adults and typically presents with seizures. Histologically, it shows features of both infiltrating glioma and ependymoma. Methods We examined molecular immunohistochemical markers which could help in distinguishing this entity from its differential diagnostic considerations. Results We retrospectively reviewed the clinicopathologic features of angiocentric gliomas and performed immunohistochemical staining for isocitrate dehydrogenase 1 (IDH-1) (R132H), p53, ATRX, BRAF V600E, Ki-67, and H3 K27M on formalin-fixed, paraffin-embedded tissue. Seven cases in total were found and included six excisional specimens and one biopsy. ATRX staining was retained in all cases. There was no evidence of staining with antibodies to IDH-1 (R132H), H3 K27M, or BRAF V600E. Five tumors showed no staining with antibody to p53 and two tumors showed less than 5% positivity. Ki-67 indices were less than 1% in five tumors, 4–5% in one tumor, and 9–10% in one tumor. Conclusions In conclusion, the immunohistochemical markers for ATRX, p53, IDH-1 (R132H), BRAF V600E, H3 K27M show wild-type staining, potentially aiding in avoiding misdiagnoses in cases morphologically similar to other low-grade gliomas. Ki-67 labeling indices are low in most tumors.

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Aims Plasma cell neoplasms (PCNs) may involve the gastrointestinal (GI) tract in two forms: plasmacytoma (PC), an isolated lesion that lacks marrow involvement, and extramedullary myeloma (EMM). However, previous literature on PCNs involving the GI tract, liver, and pancreas is limited. We evaluated the clinicopathologic features of the largest series of GI PCNs to date. Methods and Results Six institutional archives were searched for GI, liver, and pancreas cases involved with PCNs. Medical records were reviewed for clinical and imaging features. Histopathologic features evaluated included involved organ, tumor grade, and marrow involvement. Overall, 116 cases from 102 patients were identified. The tumors most presented as incidental findings (29%). The liver was most involved (47%), and masses/polyps (29%) or ulcers (21%) were the most common findings. Most cases had high‐grade morphology (55%). The majority (74%) of GI PCNs were classified as EMM due to the presence of marrow involvement at some point during the disease course, occurring within a year of marrow diagnosis in 46% of patients. PC was classified in 26% of patients due to the lack of marrow involvement. Most (70%) patients died from disease within 10 years (median 14.1) of diagnosis and more than half (58%) died within 6 months. Conclusion PC and EMM involving the GI tract, liver, and pancreas have a wide range of clinicopathologic presentations. Tumors may occur virtually anywhere in the GI tract or abdomen and may precede the diagnosis of marrow involvement. Both GI PC and EMM are associated with a poor prognosis.

Well-differentiated/dedifferentiated liposarcoma (WDLPS/DDLPS) represent a significant number of sarcomas arising within the paratesticular region. DDLPS is notorious for a broad histologic spectrum, but epithelioid morphology is rare. Herein, we describe a unique case of paratesticular DDLPS with prominent epithelioid features and molecular confirmation. The patient is 71-year-old-male who presented with multiple paratesticular masses. Morphologic review of the resection specimen revealed a biphasic adipocytic neoplasm consistent with DDLPS. Additionally, epithelioid foci with acinar and nested architecture and focal keratin expression were noted. These areas raised the possibility of a secondary neoplasm including sex cord stromal tumor, germ cell tumor, and paraganglioma. However, MDM2 immunohistochemistry and FISH showed these areas to express MDM2 and exhibit MDM2 amplification, respectively, confirming that they represented a component of DDLPS. This case further highlights the morphologic diversity of DDLPS as well as the utility of MDM2 studies.

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