Case Report: An exceptionally large spindle cell lipoma of the popliteal fossa

Background: Spindle cell lipoma (SCL) is an uncommon subtype of lipomas. It usually occurs in the posterior side trunk such as neck, back and shoulders rarely touches extremities. Only four cases SCL knee no popliteal fossa have been reported literature. We present herein largest case to our knowledge. Case presentation: A 75-year-old woman presented with a slow growing swelling left knee. Physical examination showed 12 cm well-limited painless mass fossa. The was pediculated central ulceration. MRI scan tumoral some non-dilated vessels draining long saphenous vein. had evidence invasion underlying tissues. patient underwent surgical resection postoperative recovery. histological revealed proliferation diffusely expressing CD34 without malignancy evidence, Ki67 index <1%. This morphological immunohistochemical aspect typical SCL. Clinical discussion: SCL rare variant occurring mostly upper trunk. or are exceptional. Clinically, it presents gradually increasing evolving history. Histologically, these tumors made spindle-shaped cells, rope-like collagen fibers mature adipocytes surrounded by fibrous capsule. Immunohistologically, spindle lipomas show diffuse strong expression CD34, lesser degree vimentin. optimal treatment marginal resection. Conclusions: represents infrequent subtype, its atypical presentation should push clinicians further investigations order rule out more worrisome malignancies.