Histiocytic Sarcoma with p16-Overexpression Presenting as Uterine Cervical Mass

A 67-year-old woman presented with post-menopausal bleeding. Physical examination and imaging revealed a cervical mass with extensive pelvic involvement and supraclavicular lymphadenopathy. Clinical diagnosis was stage IVB cervical carcinoma. Cervical biopsy revealed high-grade squamous intraepithelial lesion and epithelioid tumor cells in the stroma. Lymph node biopsy revealed metastasis by similar epithelioid tumor cells. The epithelioid tumor cells were positive for p16, CD68, and CD163 on immunohistochemical study. The diagnosis of histiocytic sarcoma (HS) was rendered. This case demonstrated a rare presentation of HS mimicking cervical carcinoma. Awareness of this rare entity with appropriate ancillary tests is essential for accurate diagnosis. In contrast to the previous postulation of p16-inactivation as the pathogenesis of HS, p16-overexpression might suggest a different pathway for tumorigenesis.