True histiocytic lymphoma of the esophagus in an HIV-positive patient: An ultrastructural study

A 56-year-old white woman, seropositive for human immunodeficiency virus fo r 18 months without signs of acquired immunodeficiency syndrome, presented with retrosternal pain and progressive dysphagia secondary to an exophytic esophageal mass. Biopsies of the tumor showed a malignant neoplasm composed of pleomorphic, noncohesive cells growing in a diffuse, sheet-like fashion . Immunohistochemically, tumor cells were nonreactive with epithelial, lymp hoid, neural, and monocyte/macrophage markers. Despite the noncontributory immunohistochemical findings, ultrastructural study of the tumor cells reve aled convincing histiocytic features. Individual cells possessed long, slen der filopodial projections, prominent Golgi apparatus, residual bodies, rar e lysosomes, and prelysosomes. Immunoglobulin heavy chain and T-cell recept or gamma gene rearrangement studies detected no evidence of a clonal gene r earrangement. The patient responded poorly to chemotherapy and died 5 month s after her initial symptom of dysphagia.