Primary plasmacytoma of the larynx: A case report and literature review.

RATIONALE: Primary laryngeal plasmacytoma is a rare form of extramedullary plasma cell neoplasm. By definition, it is confined to the larynx without involvement of the bone marrow or peripheral blood. To our best knowledge, there are only 51 cases reported in English literature. We report a case of primary plasmacytoma of the larynx, focusing on the clinical features, pathological diagnosis, treatment, and prognosis of this rare entity.

PATIENT CONCERNS: The patient is a 64-year-old Asian male who presented with hoarseness and a sensation of a foreign body in the throat.

DIAGNOSES: Laryngoscopy revealed a gray-white mass in the left laryngeal ventricle, raising suspicion of a pathological lesion and prompting a biopsy for diagnostic evaluation. Histopathological examination demonstrated a diffuse, invasive proliferation of abnormal plasma cells. Immunohistochemical analysis showed diffuse positivity for CD138 and exhibited restricted expression of kappa light chain in plasma cells. Based on the morphological and immunohistochemical findings, a diagnosis of primary plasmacytoma of the larynx was established.

INTERVENTIONS: The patient underwent radiotherapy treatment.

OUTCOMES: During 1 year of follow-up, no signs of recurrence or progression were observed.

LESSONS: Given its rarity, primary plasmacytoma of the larynx must be distinguished from plasma cell myeloma involving the larynx, certain types of lymphoma, malignant melanoma, and myoepithelial carcinoma. Pathological examination remains essential for accurate diagnosis.