URETHRAL CARUNCLE WITH ATYPICAL STROMAL CELLS SIMULATING LYMPHOMA OR SARCOMA - A DISTINCTIVE PSEUDONEOPLASTIC LESION OF FEMALES - A REPORT OF 6 CASES

Six urethral caruncles in women aged 32 to 82 (average, 56) years cont ained atypical stromal cells raising concern for a neoplasm. The atypi cal cells varied from spindled to round, the latter predominating, and typically had scant cytoplasm. A minority of the cells were binucleat ed or multinucleated and often had prominent nucleoli. A single mitoti c figure was found in the atypical cells in one case. The atypical cel ls were characteristically present in an edematous background containi ng numerous inflammatory cells and were focally crowded together in fi ve cases. The differential diagnosis in these cases included a florid reactive proliferation of lymphoid cells, but immunohistochemical stai ns failed to support a lymphoid nature for the atypical cells and also helped to exclude malignant lymphoma, the neoplasm most often simulat ed, Because of the invariable additional component of atypical spindle cells resembling those described in the stroma of the lower female ge nital tract and in polyps in a variety of sites, the round cells likel y represent a variant of this atypical mesenchymal cell, Similar round mesenchymal cells have also been documented in the gastrointestinal t ract, especially the stomach. Immunohistochemical stains in this serie s showed them to be positive for vimentin in four of four cases and fo r alpha smooth-muscle actin in two of four cases. The prominence of at ypical round stromal cells in these cases appears to be a distinctive feature of some urethral caruncles. The presence of these cells should not lead to misinterpretation of the lesion as a neoplastic process.