The current classification of Spitz neoplasms in the World Health Organization (WHO), Fourth Edition defines Spitz neoplasms as melanocytic proliferations with characteristic Spitz morphology and a Spitz-associated genomic fusion or HRAS mutation. In contrast, melanocytic neoplasms with BRAF mutations are considered typical of common acquired nevi, dysplastic nevi, and melanomas from intermittent sun-damaged skin. However, increased utilization of ancillary testing methods such as BRAF V600E immunohistochemistry and sequencing studies have made apparent a subgroup of benign-grade and intermediategrade melanocytic neoplasms with Spitzoid morphology that harbor BRAF V600E mutations. We refer to these cases as BRAF mutated and morphologically Spitzoid (BAMS) nevi and tumors. Two experienced dermatopathologists reviewed a series of 36 BAMS nevi/tumors. Cases in which a diagnosis of melanoma was favored were excluded. The histomorphologic, clinical, and molecular findings were assessed by immunohistochemistry, fluorescence in situ hybridization, and next-generation sequencing using validated gene panels. Characteristics of BAMS nevi/tumors were compared with a control set of Spitz tumors with previously reported fusion proteins. BAMS nevi/tumors had a decreased proportion of Kamino bodies (P = 0.03) and a higher proportion of cytoplasmic pigmentation (P < 0.00001). There were no differences in other morphologic features such as the silhouette, epidermal hyperplasia, pagetosis, and cytologic atypia compared with fusion-induced Spitz tumors. In 6/17 cases where nextgeneration sequencing studies were available, recurrent mutations in the KMT gene family were seen. This was higher than the proportion of such mutations seen in fusion Spitz tumors and lower than the frequency in cutaneous melanoma.

Desmoplastic small round‐cell tumor (DSRCT) is a rare, aggressive malignant tumor, which in the great majority of cases arises at abdominal‐pelvic sites. Nevertheless, rare cases of primary extra‐abdominal tumors have been reported. In challenging cases, its molecular hallmark, the EWSR1‐WT1 reciprocal translocation, can be exploited diagnostically by various molecular techniques. Herein, we report an extremely rare case of primary subcutaneous DSRCT in an effort to raise awareness among our dermatopathology colleagues by expanding the differential of superficial round‐cell tumors.

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Background Intramedullary lipomatous tumors are rare and mostly reported in the metaphysis of the femur, tibia, and fibula. Myelolipomas are very rare tumors composed of adipose tissue and hematopoietic cells commonly reported in adrenal gland. We report the first reported case of intraosseous myelolipoma with a pathologic fracture in a young woman. Case presentation Patient is a young woman who carried a diagnosis of systemic lupus erythematosus, antiphospholipid syndrome, and hyperparathyroidism. Radiologic studies were done after the patient reported right lower leg pain lasting for a month. Radiologic examination showed a large osteolytic lesions with pathologic fracture affecting the medial aspect of the proximal tibia with extensive soft tissue calcification. The initial clinical and radiographic suspicion was brown tumor secondary to the hyperparathyroidism. Curettage of the lesion yielded large fragments of mature adipose tissue punctuated by a variable amount of mature hematopoietic cells. The histopathologic features were suggestive of myelolipoma. The overall radiographic and histopathologic features supported a diagnosis of myelolipoma. The diagnosis of intraosseous myelolipoma can be challenging in small samples such as core biopsies. Conclusions The differential diagnoses of intraosseous myelolipoma include normal bone marrow, intramedullary hematopoiesis, and other benign lesions. The gold standard diagnosis is histopathologic examination. However, clinical and radiographic features have important roles in the diagnosis of this rare lesion. Due to the rarity of this tumor and lack of formal guidelines for management, the case-to-case basis treatment is recommended.