Plasmablastic lymphoma of the oral cavity in an HIV-positive child.

A 7-year-old boy with a positive history of vertical HIV transmission presented with a painful swelling over the left upper jaw of 20 days' duration. A provisional diagnosis of non-Hodgkin's lymphoma or embryonal rhabdomyosarcoma was made. Fine-needle aspiration cytology findings were inconclusive, and incisional biopsy tissue on routine stains gave an impression of small round cell tumor with plasmacytoid features. A series of histochemical stains and immunohistochemical studies was carried out to differentiate and characterize this tumor. The salient immunostaining was negativity with all routine small round cell tumor markers and positivity with CD138 and lambda light chain restriction. The heterogeneous presentation of plasmablastic lymphoma as a variant of diffuse large B-cell lymphoma and its histogenesis is documented. Potential pitfalls and differential characterization of AIDS-plasmablastic lymphoma from other closely related tumors are addressed. The importance of excluding other common pediatric small round cell tumors by immunohistochemistry is highlighted. To the best of our knowledge, this is the first report of this entity in a vertically transmitted HIV-positive child.