Histological and immunohistochemical characterization of extranodal diffuse large-cell lymphomas with prominent spindle cell features

Aims: To describe five cases of diffuse large-cell lymphoma with prominent spindle cell components involving skin, nasal-ocular mucosa, and soft tissu e. Because of the spindle cell morphology, such cases must be differentiate d from true sarcomas arising in or metastasizing to soft tissue. skin. bone . lymph node. or other organs and sites. Methods and results: Formalin-fixed paraffin-embedded archival tissue from five consultation cases of diffuse large-cell lymphoma with prominent spind le cell features involving the skin, nasal-ocular mucosa. and soft tissue i n three male and two female patients wits studied by histology and immunohi stochemistry. Clinicopathological findings were also reviewed for all the p atients. By morphology, initial evaluation of the cases suggested spindle c ell sarcoma in two cases, inflamma tory pseudotumour in one case, large-cel l lymphoma in another case. and one case was considered suspicious for mali gnant lymphoma. Immunohistochemistry demonstrated a B-cell lineage in four of the spindle cell lesions. with it diagnosis of primary cutaneous CD30+ a naplastic large cell lymphoma made for the fifth case. Four of five cases a lso showed actin reactivity. Conclusions: Although extremely rare. lymphomas with prominent spindle cell morphology can be encountered in daily surgical pathology practice, and sh ould be included in the differential diagnosis of spindle cell lesions in s kin and soft tissue. The observed actin reactivity in four of the five spin dle cell lymphomas may lead to a misdiagnosis of leiomyosarcoma if lymphoid markers are not included in the immunohistochemical panel.