Nonsebaceous lymphadenoma in the parotid gland: true neoplastic or reactive? A report of two cases

Reevaluation of Salivary Lymphadenoma: A Subgroup Identified as Warthin-like Mucoepidermoid Carcinoma Following Molecular Investigation for MAML2 Rearrangement

CONTEXT.—

Both salivary lymphadenomas (LADs) and Warthin-like mucoepidermoid carcinoma (MEC) contain components of epithelium and lymphoid stroma and their differential diagnosis can be difficult on the basis of morphology alone.

OBJECTIVE.—

To clarify whether Warthin-like MEC was diagnosed as a LAD, and to compare their clinicopathologic features.

DESIGN.—

A total of 16 LAD cases were analyzed for MAML2 rearrangement by using fluorescence in situ hybridization, and the clinical, histologic, immunohistochemical, and prognostic features were compared between MAML2 rearrangement-positive and MAML2 rearrangement-negative groups.

RESULTS.—

Among the 16 cases investigated, 9 harbored a MAML2 rearrangement and were reclassified as Warthin-like MEC. The remaining 7 cases were classified as LADs with 1 nonsebaceous and 6 sebaceous cases. The patients with Warthin-like MEC had a wider age range (10-75 years) than the patients with LADs (36-68 years). Histologically, 2 of the 9 Warthin-like MECs (22.2%) showed focal invasion, whereas all the LADs had complete capsules. Warthin-like MECs exhibited a diverse epithelial cell morphology, including basaloid, glandular, cuboidal, epidermoid, with mucinous cells, although these cytologic features were seen only focally in some cases. Nonsebaceous LAD was composed of basaloid and glandular epithelial cells predominantly. In sebaceous LAD, the epithelial cells were composed of basaloid and large foamy sebaceous cells. In all cases, the stroma was composed mainly of lymphocytes accompanied by lymphoid follicles, although plasma cell infiltration could be much heavier in Warthin-like MEC. All the patients had a good outcome after a longer follow-up (3-166 months).

CONCLUSIONS.—

Warthin-like MEC can be misdiagnosed as a LAD owing to overlap in clinicopathologic features of the 2 entities. Careful histologic evaluation and detection of MAML2 rearrangement can facilitate their differential diagnosis.

Malignant Transformation of Parotid Gland Non-sebaceous Lymphadenoma: Case Report and Review of Literature

Non-sebaceous lymphadenoma is a sporadic benign tumor of salivary glands. Histopathologic and immunohistochemical properties, diagnostic criteria, and theories for the histologic origin of the disease have been defined and well-discussed in the literature. However, none of the cases showed malignant transformation to date. We reported a case of 54 years old female patient with a right preauricular mass. Magnetic resonance imaging demonstrated a 2 cm, well-defined contrast-enhanced mass in the right parotid gland. Fine needle aspiration cytology was undiagnostic but suspicious for malignancy. Total parotidectomy with facial nerve preservation was done. In the histopathological examination, non-sebaceous lymphadenoma regions and malignant cells with abundant cytoplasm, large vesicular nuclei, and prominent nucleoli, which occupied approximately 70% of the mass, were seen. The diagnosis was undifferentiated carcinoma arisen from non-sebaceous lymphadenoma. Adjuvant radiotherapy was given. No recurrence was detected during ten months of follow-up. This case is the first case of a malignancy developed from non-sebaceous lymphadenoma.

Parotid Gland Non-Sebaceous Lymphadenoma: A Case Report

We here report a rare salivary gland tumor, a non-sebaceous lymphadenoma (NSLA), in the parotid gland with positive technetium-99m (99mTc) pertechnetate scintigraphy and cervical masses that was difficult to distinguish from malignant lymphoma preoperatively. A 65-year-old Japanese woman presented to our institution with a painless left parotid mass that had been gradually enlarging for three months. Computed tomography and magnetic resonance imaging showed a solid mass (30 mm) in the tail of the left parotid gland with three swellings (each 10 mm) on the periphery of the parotid gland. A low grade malignant lymphoma was diagnosed by fine needle aspiration cytology. Gallium-67 scintigraphy showed mild positivity. On 99mTc pertechnetate scintigraphy, the mild accumulation remained after oral stimulation with a mixture of ascorbic acid and calcium pantothenate. The patient underwent superficial parotidectomy with removal of the cervical masses. Our findings in this patient suggest that 99mTc positivity may constitute a clue to the preoperative diagnosis of NSLA that has pathologically overlapping sites with Warthin tumor.