Plasmablastic Lymphoma in the Submandibular Region Diagnosed by FNAC: A Case Report and Literature Review.

Objective: This study aims to provide a literature review of FNAC-diagnosed plasmablastic lymphoma (PBL) cases and present a case of PBL in an HIV patient diagnosed by FNAC.

Methods: A literature review was conducted across eight databases to compile information on FNAC-diagnosed PBL cases without restricting the site of involvement.

Results: The literature review included 23 PBL, with 13 (56.5%) affecting head and neck region. The mean age of patients was 49 years, with a male-to-female ratio of 1.9:1, and 13 (56.5%) patients were HIV positive. Ten (43.5%) of 23 patients tested positive for Epstein-Barr virus (EBV). Twenty-one FNAC procedures and two cytological smears were performed. Plasmacytoid/plasmablastic morphology was described in seven cases (30.4%). Large cells were observed in 17 cases (73.9%). Pleomorphism was noted in 10 cases (43.5%). A cytological diagnosis of malignancy was achieved in 91.3% of cases. In 20 cases assessed for concordance, complete agreement was found in 8 cases (34.8%), while discordance was noted in 12 cases (65.2%). We also report a case of PBL diagnosed via FNAC in a 55-year-old male patient who presented with a painful, hard, nonmobile mass in the left submandibular region, approximately 10 cm in size, with 1 month of evolution. FNAC was performed, and cytologic smears, along with cell block (CB) preparations, were made. After staining with Diff-Quik, HE and Papanicolaou stain, numerous cells exhibiting plasmacytic morphology were observed. Immunohistochemical analysis showed negativity for LCA, CD3, CD20, Pax5, CD79a, ALK and HHV-8, and positivity for CD138, MUM1 and Ki-67 (100%). EBV positivity was also confirmed, leading to a diagnosis of PBL.

Conclusion: This study highlights the efficacy of FNAC in diagnosing PBL. The immunophenotypic profile and morphological features observed through FNAC, combined with immunohistochemistry (IHC) and in situ hybridisation, were crucial for an accurate diagnosis. The literature review underscores the value of FNAC as a diagnostic tool for PBL, demonstrating a high rate of cytological diagnosis and significant cytohistological concordance.