Cytologic features of plasmablastic lymphoma

Plasmablastic lymphomas (PBLs) were originally described exclusively in human immunodeficiency virus (HIV)-positive patients who presented with jaw or oral mucosa involvement. Recent studies have reported this neoplasm also in patients without HIV infection and involving sites other than head and neck. This lymphoma has a heterogeneous morphologic presentation but distinct phenotype.

Cytologic features from four cases of histologically confirmed PBL were evaluated. The cytology specimens were evaluated for criteria as follow: cellularity, cell size and shape, pleomorphism, cytoplasmic characteristics, chromatin pattern, nucleolar features, and mitotic figures.

Specimens evaluated were two head and neck fine needle aspiration specimens, one anal smear, and one cerebrospinal fluid specimen. Atypical lymphocytes ranged from intermediate to large in size and demonstrated slight nuclear pleomorphism. The cytoplasm varied from scant to moderate in the alcohol-fixed slides. Nuclei were round with vesicular chromatin. Nucleoli varied from a prominent one to multiple small ones. Multinucleated cells and mitotic figures were easily identified in three of four cases. Tingible-body histiocytes were seen in one case. Ancillary studies in two cases demonstrated expression of CD138 with lack of CD20 expression.

PBL is a variant of large cell lymphoma with heterogeneous cytologic findings but distinct immunophenotype. Knowledge of the cytomorphologic spectrum of PBLs and detection of CD138 expression by flow cytometry can be helpful in achieving a correct diagnosis.