Cytomorphological features of an unusual case of a multifocal pseudomyogenic (epithelioid sarcoma-like) hemangioendothelioma in a young adult male.

Pseudomyogenic (epithelioid sarcoma-like) hemangioendothelioma (PMHE) is a relatively newly described vascular neoplasm, characterized by distinct clinicopathological and molecular features, with no report on its cytomorphological features on smears, till date. A 17-year-old male presented with multiple nodules on his left upper limb. Radiologic imaging disclosed multiple lesions involving the soft tissues, skin, and bones of his left upper limb. Biopsy of one of the lesions on his left ring finger revealed a cellular tumor comprising plump spindle and epithelioid cells, containing moderate to abundant, eosinophilic cytoplasm; mild nuclear atypia, vesicular nuclear chromatin, discernible nucleoli, infrequent mitotic figures, and interspersed neutrophils. Immunohistochemically, tumor cells were positive for AE1/AE3, CD31, and FLI-1, while negative for CD34 and desmin. INI1/SMARCB1 was retained. MIB1/Ki67 highlighted nearly 3% tumor cells (low). Diagnosis of a PMHE was offered. A simultaneous fine needle aspiration cytology smears of the lesions in his left forearm and ipsilateral axillary region revealed spindle and some polygonal shaped cells, arranged in tight and loose clusters, as well as scattered singly, containing abundant cytoplasm with tapering cell membranes, at places; vesicular nuclear chromatin and characteristic intercellular fibrillary stromal material. The present case constitutes the first report on cytomorphological features of a PMHE, diagnosed on cytology, including its differential diagnoses, immunohistochemical features with molecular updates.