| Description: |
Statement of Purpose: This case presents a rare sclerosing-type atypical lipomatous tumor with myxomatous features—the first and only known reported case of an ALT in the foot—along with its pathology, treatment, and management. Case Study: Atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDL) represents the most common liposarcoma subtype, with recurrence and dedifferentiation risk influenced by tumor location. Retroperitoneal tumors recur frequently, while those in the lower extremity rarely do. Liposarcoma of the foot is exceedingly rare. A 61-year-old male presented with a slowly enlarging, mildly tender lump on the right plantar heel. Radiographs demonstrated a 3 cm oval soft-tissue thickening without calcification. MRI revealed a 2.7 × 3.4 × 1.8 cm well-circumscribed subcutaneous lesion in the calcaneal fat pad, T1 hypointense, T2 hyperintense, and showing inhomogeneous post-contrast enhancement, with no invasion of plantar musculature or osseous structures. After 8 months of conservative observation, the patient elected excision due to progressive growth and discomfort. A 5 cm lazy-S incision exposed a 4.2 × 3.2 cm encapsulated mass. The lesion was widely excised with 1 cm margins, and both the mass and peripheral tissue were submitted for pathological analysis. Layered closure and a short CAM walker were applied, with two weeks non–weight-bearing with crutches followed by progressive loading. Results: Gross pathology revealed a 3.6 × 2.8 × 1.8 cm glistening, ovoid mass weighing 11 grams. Microscopic examination confirmed the diagnosis of an atypical lipomatous tumor, sclerosing subtype, with prominent myxomatous features. Histological sections demonstrated small adipocytes surrounded by myxomatous stroma and irregular fibrous connective tissue. Trichrome and Alcian blue staining highlighted collagen and myxoid components, respectively. Immunohistochemical analysis revealed negative staining for S100, epithelial membrane antigen (EMA), desmin, and synaptophysin, but positive for MDM2, ... |