Multifocal Adenomatous Oncocytic Hyperplasia of the Parotid Gland

Abstract

Multifocal adenomatous oncocytic hyperplasia (MAOH) is a non-neoplastic lesion that is classified as oncocytosis. MAOH is a rare entity of the parotid gland and accounts for approximately 0.1% of salivary gland lesions. Here, we report a case of MAOH of the parotid gland. The patient was a 71-year-old woman who presented with discomfort at the left side of her neck. Fine-needle aspiration cytology of the parotid gland revealed a loose sheet-like cluster of round to polygonal cells with granular cytoplasm against a hemorrhagic background. The cells had round to oval, centrally located nuclei with granular chromatin and without distinct nucleoli. Histologically, the lesion was formed of many variable-sized nodules, comprising oncocyte-like cells with small round nuclei and eosinophilic granular cytoplasm that was positive for mitochondrial antibodies. The diagnosis of MAOH is difficult to make by cytology alone, because the findings overlap with those of other oncocytic lesions. In particular, the cytological findings of MAOH have not been sufficiently reported to date. A correlation of cytology and histology was expected.

Nodular oncocytic hyperplasia: Can cytomorphology allow for the preoperative diagnosis of a nonneoplastic salivary disease?

“…Unfortunately, there are many benign and malignant salivary conditions that enter the differential diagnosis of oncocytosis, including Warthin tumor, oncocytoma, papillary oncocytic cystadenoma/cystadenocarcinoma, salivary duct carcinoma, acinic cell carcinoma, mammary analog secretory carcinoma (MASC), and oncocytic mucoepidermoid carcinoma. Moreover, only a few reports previously have described the cytologic characteristics of oncocytosis cases that might help facilitate this distinction . Herein, we evaluated FNA findings in what to our knowledge is the largest series of oncocytosis cases reported to date in the hopes of allowing the confident preoperative diagnosis of this condition.…”

“…These findings are similar to those noted in previous case reports of oncocytosis cytology. [7][8][9] Although the features described herein are not entirely specific, they should both support the inclusion of oncocytosis in the preoperative differential diagnosis and allow oncocytosis to be favored over other salivary gland lesions with oncocytic features in the appropriate clinical and radiographic setting.…”

“…Although there was some variability between specimens, we identified a characteristic pattern of paucicellular smears comprised of small groups of oncocytic cells in the majority of FNA specimens of oncocytosis. These findings are similar to those noted in previous case reports of oncocytosis cytology . Although the features described herein are not entirely specific, they should both support the inclusion of oncocytosis in the preoperative differential diagnosis and allow oncocytosis to be favored over other salivary gland lesions with oncocytic features in the appropriate clinical and radiographic setting.…”

“…Moreover, only a few reports previously have described the cytologic characteristics of oncocytosis cases that might help facilitate this distinction. [7][8][9] Herein, we evaluated FNA findings in what to our knowledge is the largest series of oncocytosis cases reported to date in the hopes of allowing the confident preoperative diagnosis of this condition.…”

The key radiologic and cytomorphologic features of oncocytic and oncocytoid lesions of the salivary gland

“…Rare variant morphologies have been focally noted, including the presence of spindled cells, squamous differentiation, and mild nuclear pleomorphism, each occurring in up to a quarter of cases . The presence of microvacuoles has been noted in liquid‐based preparations …”