Cutaneous spindle-cell B-cell lymphoma - A morphologic variant of cutaneous large B-cell lymphoma

The morphologic spectrum of large B-cell lymphoma is broad. Several unusual variants have been described such as lymphoma with myxoid stroma, sclerosi ng B-cell lymphoma, signet ring-cell lymphoma, and multilobated B-cell lymp homa among others. We report on five cases of cutaneous large B-cell lympho ma in which the neoplastic cells were spindle-shaped. In two cases, the cli nical features fulfilled those of a primary cutaneous lymphoma; in the thre e other cases, the lymphoma most likely arose primarily in the skin, but in complete clinical workups precluded definite categorization. The patients r anged in age from 30 to 89 years and presented with solitary lesions on the trunk or head. Histopathologic examination revealed nodular or dense diffu se infiltrates involving the entire dermis as well as the subcutaneous fat in some cases. Thickened collagen bundles between the spindled cells were p resent in one case. Cytomorphologic analysis showed the presence of round o r oval medium-sized and large-sized lymphocytes with features of centrocyte s and centroblasts in some foci, with others dominated by cells with spindl e-shaped, elongated, twisted nuclei with dispersed chromatin and scant cyto plasm. Immunohistologic analysis revealed that both round or oval and spind led cells were positive for CD20 in all cases; in all cases tested, these c ells were also positive for MIB-1 and were negative for CD3, CD5, CD43, CD4 5RO, CD21, CD30, CD68, S-100, HMB-45, actin, smooth-muscle actin, and cytok eratin. Bcl-2 was expressed in one of three cases tested. Analysis of the r earrangement of the J(H) gene by polymerase chain reaction performed in one case showed a monoclonal pattern. Spindle-cell large B-cell lymphoma repre sents a distinctive rare subtype of the cutaneous large B-cell lymphoma and can arise primarily in the skin in some cases. Recognition of this variant is necessary to avoid misdiagnosis of other cutaneous malignant spindle-ce ll tumors.