Cutaneous granulocytic sarcoma mimicking immunoblastic large cell lymphoma

A peculiar case of cutaneous granulocytic sarcoma without leukemic manifest ation (so-called aleukemic leukemia cutis) that developed in the skin of th e back of a 69-year-old man is reported. A skin biopsy specimen showed atyp ical cells with a prominent nucleolus proliferating around dermal blood ves sels and along adnexa without epidermotropism. Atypical cells similar to th ose of the skin had infiltrated diffusely into the interfollicular area of an inguinal lymph node. Flow cytometric and immunohistochemical studies wit h a panel of monoclonal antibodies revealed neoplastic cells that had a bip hasic phenotype of myeloid and T cell precursors. They expressed CD13, CD15 , CD33, lysozyme, CD3 epsilon, CD4, CD7 and terminal deoxynucleotidyl trans ferase (TdT). Gene analysis showed no rearrangement of the immunoglobulin h eavy chain or T cell receptor beta and gamma genes. Ultrastructurally, the tumor cells exhibited a few intracytoplasmic electron-dense granules and we ll-developed rough endoplasmic reticulum with an occasional whorling arrang ement. The initial diagnosis was immunoblastic large cell lymphoma, and the patient was treated with six courses of ProMACE-CytaBOM. In spite of the h igh-grade cytological characteristics of this tumor, the patient has been f ree of disease for 5 years.