Non-sebaceous Lymphadenoma of the Parotid Gland Mimicking a Pleomorphic Adenoma

Non-sebaceous lymphadenoma of the salivary glands is a rare benign lesion, first described in 1991. We present the case of a 54-year-old woman, with a right parotid mass. She underwent right superficial parotidectomy, and histopathology reported a non-sebaceous lymphadenoma due to an encapsulated lesion and multiple non-atypical epithelial inclusions without sebaceous differentiation. The etiology of non-sebaceous lymphadenoma is not yet understood, but it can arise predominantly from the parotid gland. Surgical excision is the treatment of choice.

Cytomorphology and diagnostic pitfalls of sebaceous and nonsebaceous salivary gland lymphadenoma: A multi-institutional study

BACKGROUND

Salivary gland lymphadenoma (LAD) is a rare benign neoplasm comprising sebaceous (SLAD) and nonsebaceous (NSLAD) types. Despite established histologic criteria, limited data on cytomorphology, tumor heterogeneity, and overlap with other entities make the diagnosis of LAD by fine needle aspiration (FNA) challenging. We describe a multi-institutional cohort of 14 LADs with cytology, clinical, radiologic, and histopathologic data.

METHODS

Our cohort included nine SLAD and five NSLAD with corresponding histopathology. Mean patient age and M:F ratio were 60.4 years (range 45-86 years) and 1:2 for SLADs and 57.4 years (range 42-80 years) and 1:1.5 for NSLADs, respectively. One NSLAD patient had a germline predisposition for Cowden syndrome. Glass slides and whole slide images of air-dried Diff-Quik (DQ), alcohol-stained Papanicolaou smears (Pap) and cellblocks were reviewed for key cytomorphologic findings.

RESULTS

FNAs from SLAD and NSLADs demonstrated vacuolated and basaloid epithelial clusters within a lymphoid background. Vacuolated cells from SLAD showed sebaceous cells with microvesicular cytoplasm indenting a central nucleus. Vacuolated cells from NSLAD were columnar with eccentric nuclei, corresponding to abluminal glandular cells. SLADs were classified using the Milan System for Reporting Salivary Gland Cytopathology as nondiagnostic (11.1%), nonneoplastic (44.4%), atypia of uncertain significance (AUS) (22.2%), and salivary gland neoplasm of uncertain malignant potential (SUMP) (22.2%). NSLADs were classified as AUS (40%), SUMP (40%) and Benign Neoplasm (20%).

CONCLUSION

Although rare, knowing the cytologic features of salivary LAD is important to avoid diagnostic pitfalls. Vacuolated cells can be prominent in both SLAD and NSLAD aspirates. Diagnostic issues arise from insufficient sampling of all tumor components leading to marked variation in diagnostic classification of LAD.

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.

Lymphadenoma of the salivary gland: Report of 10 cases

Lymphadenoma of the salivary gland is rare, and the typical characteristics of lymphadenoma remain poorly understood. The aim of this study was to analyze the experience of a single institution in the clinical diagnosis, treatment and prognosis of this type of tumor of the salivary gland. All cases of lymphadenoma diagnosed at the institution between 1996 and 2012 were analyzed. The clinical information (including age, gender and tumor location, process of tumor development, imaging data, surgical treatment and follow-up information) and pathological features were evaluated. All tumors occurred in the parotid glands; three cases were sebaceous lymphadenoma (two male and one female) and seven were non-sebaceous lymphadenoma (three male and four female). The average ages of the patients were 68.3 and 42.4 years for the sebaceous and non-sebaceous groups, respectively. The majority of cases (90%) were diagnosed as pleomorphic adenoma or adenolymphoma prior to surgery, but were confirmed as lymphadenoma by pathological analysis following surgery. During the follow-up period, which ranged between 3 and 36 months with a mean of 30 months, no recurrence of the lesion was identified and the quality of life was good for each patient. In conclusion, the diagnosis of salivary gland lymphadenoma should be based on the clinical and, in particular, the pathological manifestations of the disease. Immunohistochemistry is considered as a practical and helpful adjuvant method of the diagnosis for this type of tumor. Complete surgical resection is the first choice of treatment. Further exploration of the histological origin of lymphadenoma of the salivary gland is necessary due to the insufficient number of reported cases.