Microscopic description:

Clear cells with distinct borders, arranged in nests

Abundant clear cytoplasm

Subtle nuclear pleomorphism

Minimal mitotic activity

FISH for EWSR1 rearrangements was positive

Discussion:

Clear cell carcinomas of salivary gland are rare tumors. Median age of diagnosis is 63 years. The incidence is equally distributed in males and females. Majority of the lesions are found in minor salivary glands.

Majority of these tumors have a EWSR1-ATF1 fusion.

Differential diagnosis for clear cell tumors of salivary gland includes Mucoepidermoid carcinoma, acinic cell carcinoma, and epithelial-myoepithelial carcinoma. Metastatic renal cell carcinoma should also be considered as a possibility. Special immunostains and presence of specific translocations help with the diagnosis.

The following immunostains are useful for differentiating the different types of clear cell tumors:


table depicting IHC stains for clear cell carcinomas
References:

Sharbel DD, Unsal AA, Groves MW, Albergotti WG, Byrd JK. Salivary Clear Cell Carcinoma Clinicopathologic Characteristics and Outcomes: A Population-Based Analysis. Ann Otol Rhinol Laryngol. 2019;128(11):989-996. doi:10.1177/0003489419853597

Shaar RA, Zia S, Alhamar M, et al. Salivary gland hyalinizing clear-cell carcinoma with cutaneous metastasis: A rare and deceptive tumor. J Cutan Pathol. 2021;48(1):86-89. doi:10.1111/cup.13799

Desai A, Rivera CM, Faquin WC, et al. Clear cell carcinoma: a comprehensive literature review of 254 cases [published online ahead of print, 2021 Oct 19]. Int J Oral Maxillofac Surg. 2021;S0901-5027(21)00128-4. doi:10.1016/j.ijom.2021.03.018

Sanjai K, Shivalingaiah D, Sharath R, Pandey B. Clear cell carcinoma of palatine salivary gland: A diagnostic challenge. J Oral Maxillofac Pathol. 2018;22(1):128-131. doi:10.4103/jomfp.JOMFP_236_17

CASE IMAGES