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non-sebaceous lymphadenoma
Thursday 17 December 2015
Definition: NSL is a rare benign salivary gland tumor with intermingled lymphoid and epithelial tissues without sebaceous differentiation. Non-sebaceous lymphadenomas are similar to sebaceous lymphadenoma but without the sebaceous component.
Cases
History
Since the first description of a case designated by Auclair et al. as ’non-sebaceous lymphadenoma’ in 1991, to 2013, only 37 cases have been reported. In 2012, only 11 non-sebaceous LAD have been reported in the literature.
Epidemiology
Unlike their sebaceous counterparts, the non-sebaceous tumors were more common in women than in men, similar to most salivary gland tumors. Additionally, 40% of the patients had extraparotid non-sebaceous LAD in contrast to sebaceous LAD that was intraparotid in nearly 90% of patients.
No other demographic, clinical, or pathologic differences were found in these two subtypes.
Some investigators argue that non-sebaceous LAD may not be a distinct entity but rather a basal cell adenoma or cystadenoma with extensive lymphoid infiltrate.
The non-sebaceous LAD tend to have more focal keratinization, less peripheral palisading, generally lack the production of basement membrane material and have a small or non-existent myoepithelial component as compared with basal cell adenomas.
Macroscopy
These tumors have ranged in size from 0.6 to 8 cm with a mean size of almost 2.5 cm. They are typically well-demarcated.
Microscopy
They are composed of a prominent lymphoid population surrounding proliferating epithelium arranged as solid tubules or basaloid islands often with a prominent trabecular arrangement with or without cyst formation.
In non-sebaceous LAD, the epithelial component comprising predominantly solid cords and trabeculae of basal cells admixed with low columnar cells around tubuloglandular spaces without any sebaceous differentiation.
Squamous differentiation with keratinization was seen less frequently (18%). Atypia is minimal and sebaceous or oncocytic differentiation is not found.
Focal squamous differentiation and mucin-secreting cells may be observed.
There appears to be two somewhat different morphologies included in this group:
One is similar to a SL (but lacking the sebaceous differentiation) with prominent microcystic change and often with focal squamous differentiation, which is the so-called “typical type”.
a second group of tumors that is composed of solid nests and interconnecting trabeculae with frequent peripheral palisading, somewhat similar to the cell population of basal cell adenoma, but with a prominent lymphoid component, thus called the “basaloid type”.
A tumor with similar morphology to the latter pattern has rarely been reported in the skin.
The lymphocytic infiltrate comprising mixed populations of B and T lymphocytes is prominent in all LAD, with germinal centers in 84% of tumors.
Stromal foreign body type giant cell granulomatous reaction is frequently noted in association with ruptured cyst in sebaceous LAD (50%) and less frequently in non-sebaceous LAD (18%).
Intraepithelial B and T lymphocytes is noted in all tumors, but were remarkable in only rare cases.
Some tumors appeared to be intranodal with intact lymph node capsule. They can also have adjacent normal salivary tissue elements within the lymph node.
Immunochemistry
Epithelial membrane antigen (EMA) immunohistochemistry typically stains collapsed spaces or small groups of cells in the central portion of the epithelial islands or trabeculae indicating subtle luminal differentiation.
Complete surgical excision is the treatment of choice. These tumors should not recur if properly excised.
Variants
serous acinic cell differentiation (23714255)
Differential diagnosis
other lymphadenomas sebaceous type
Warthin tumor ( cystadenolymphoma )
salivary carcinomas
Open references
Lymphadenoma of the salivary gland: Report of 10 cases. Liu G, He J, Zhang C, Fu S, He Y. Oncol Lett. 2014 Apr;7(4):1097-1101. PMID: 24944675
Non-sebaceous lymphadenoma of the salivary gland with serous acinic cell differentiation, a first case report in the literature. Ishii A, Kawano H, Tanaka S, Yamamoto Y, Nakamoto T, Hirose Y, Yamashita H, Morinaga S, Ikeda E. Pathol Int. 2013 May;63(5):272-6. doi : 10.1111/pin.12061 PMID: 23714255
My journey into the world of salivary gland sebaceous neoplasms. Gnepp DR.
Head Neck Pathol. 2012 Mar;6(1):101-10. doi : 10.1007/s12105-012-0343-x PMID: 22430772 (Free)
Lymphadenoma of the salivary gland: clinicopathological and immunohistochemical analysis of 33 tumors. Seethala RR, Thompson LD, Gnepp DR, Barnes EL, Skalova A, Montone K, Kane S, Lewis JS Jr, Solomon LW, Simpson RH, Khan A, Prasad ML.
Mod Pathol. 2012 Jan;25(1):26-35. doi : 10.1038/modpathol.2011.135 PMID: 21892186 (Free)