Crystalloid Granuloma of Parotid Gland: A Case Report With Review of the Literature

Abstract

Crystalloid granuloma (CG) of salivary gland is an extremely rare inflammatory disease, and only 6 cases have been reported in the English literature. CG is histologically characterized by a granulomatous reaction to amylase crystalloid deposition. A 73-year-old woman presented with a painful left neck mass. Computed tomography depicted a mass located in the lower pole of the left parotid gland, suspicious for a tumoral lesion. Preoperative fine needle aspiration cytology found amylase crystalloid deposition with a few inflammatory cells. Surgical sections of the mass revealed formation of a granuloma containing abundant eosinophilic but glassy and transparent amorphous crystalloids, suggestive of α-amylase crystalloid. No neoplastic elements were detected. The case was eventually diagnosed with CG in the parotid gland. Our findings suggest that when we identify amylase crystalloids in fine needle aspiration cytology smears from the salivary gland, CG should be considered even if neoplasm is clinically or radiographically suspected.

The Milan System classification of Warthin tumor: A large institutional study of 124 cases highlighting cytologic features that limit definitive interpretation

“…Amylase crystalloids are crystalline structures that are variably rhomboid, rectangular, and needlelike in shape that are predominantly associated with nonneoplastic salivary gland disease, such as sialadenitis and benign cysts, but can also be found associated with neoplastic lesions including WT and pleomorphic adenoma. [20][21][22][23][24][25][26][27][28] Amylase crystalloids are likely an underrecognized and underreported finding in cytology (in all 3 cases in the current study cohort, amylase crystalloids were not noted on prospective review). However, their recognition can be helpful especially for FNA cases where a malignant lesion is being considered.…”

Crystals and crystalloids in cytopathology: Incidence and importance

“…[10][11][12] Amylase crystalloids are mostly associated with nonneoplastic conditions including duct obstruction, sialadenitis, oncocytic cysts or cystadenomas, developmental cysts, and lymphoepithelial cysts. 1,[10][11][12][13][14][15][16][17][18] They have also been reported in association with Warthin tumors, which are benign neoplastic lesions. 1,19 Based on the current literature, amylase crystalloids have not been found in association with malignancy.…”

Crystalloids in FNA specimens of salivary gland lesions: A retrospective study in a single large institute

“…They have been found predominantly in association with nonneoplastic salivary gland disease, which includes sialadenitis, obstructive cysts, and crystalloid granuloma, although they have also rarely been found in association with some neoplastic lesions, including Warthin tumor and pleomorphic adenoma. [2][3][4][5][6][7][8][9] It has been indicated that the presence of a cystic space, which results from salivary stasis, is crucial for the formation of amylase crystalloids, likely because α-amylase becomes condensed in supersaturated saliva and undergoes crystallization in the cystic space. 6,8,9 Tyrosine crystalloids, conversely, have been identified more frequently in association with salivary gland neoplasms, most commonly benign neoplasms and specifically pleomorphic adenomas; however, there have been rare reported cases of tyrosine crystalloids in adenoid cystic carcinoma and polymorphous (low-grade) adenocarcinoma.…”