Atypical Spindle Cell/Pleomorphic Lipomatous Tumour ( <scp>AS</scp> / <scp>PLT</scp> ) – An Emerging Entity Diagnosed on Fine Needle Aspiration Cytology

Atypical spindle cell/pleomorphic lipomatous tumour (AS/PLT) is a novel entity described under the benign lipomatous neoplasm recognised by the recent WHO classification of soft tissue tumours (fifth edition). In this report, we present a case of a 44-year-old male who with a swelling on dorsum of the hand measuring 8 × 8 cm. A Fine needle aspiration cytology (FNA) was performed which revealed adipocytic fragments with individual cells exhibiting mild to moderate nuclear atypia with floret like cells, multinucleated giant cells along with few pseudo-lipoblast-like cells. Based on cytomorphological findings a possibility of an Atypical spindle cell/Pleomorphic lipomatous tumour [AS/PLT] was given. An excision was performed which revealed features confirmed the diagnosis of an AS/PLT. MDM-2 Immunohistochemistry was performed and was negative ruling out a well differentiated Liposarcoma. Hence, the diagnosis was confirmed on histopathological examination. AS/PLT is a unique novel benign neoplasm with a slightly higher recurrence rate than a Pleomorphic lipoma. Here, we discussed the characteristic cyto-morphological features of an AS/PLT that help in the diagnosis and guide further surgical management.