Abstract
BackgroundOncocytic carcinoma is an extremely rare neoplasm of the salivary glands. We report a case of oncocytic carcinoma arising in a parotid gland in a 66-year-old female.MethodAn excisional biopsy of the parotid tumor was performed. The specimen was submitted for histology and after fixation in formalin solution and inclusion in paraffin, 3–5 μm sections were stained with hematoxylin and eosin for conventional evaluation and Periodic acid Schiff stain. Immunohistochemical studies were performed using antibodies against mitochondrial antigen, keratin, S-100, alpha-actin, vimentin, alpha-1-antichymotrypsin as well as an ultrastructural analysis was performed.ResultsFrozen sections revealed an infiltrative growth pattern and the diagnosis of a malignant epithelial lesion was made. Permanent sections stained with haematoxylin and eosin revealed a neoplasm that had replaced a wide area of the parotid gland and had invaded subcutaneous adipose tissue. Perineural invasion was evident, but vascular invasion was not found. Neoplastic elements were large, round or polyhedral cells and were arranged in solid sheets, islands and cords. The cytoplasm was abundant, eosinophilic and finely granular. The nuclei were large and located centrally or peripherally. The nucleoli were distinct and large. Periodic acid Schiff stain demonstrated a granular cytoplasm. Immunohistochemistry demonstrated mithochondrial antigen, keratin, and chymotrypsin immunoreactivity in the neoplastic cells. Ultrastructural analysis revealed numerous mitochondria packed into the cytoplasm of the neoplastic cells. Thus, the final diagnosis was that of oncocytic carcinoma of parotid gland.ConclusionThis neoplasm shows clinical, microscopical, histological and ultrastructural features of oncocytic carcinoma and this must be considered in the differential diagnosis of other proliferations in the parotid gland with abundant granular cytoplasm and metastatic oncocytic carcinomas.
Highlights
Oncocytic carcinoma is an extremely rare neoplasm of the salivary glands
Permanent sections stained with haematoxylin and eosin revealed a neoplasm that had replaced a wide area of the parotid gland and had invaded subcutaneous adipose tissue
Ultrastructural analysis revealed numerous mitochondria packed into the cytoplasm of the neoplastic cells
Summary
The tumour was a well-circumscribed, firm, grey-brown, ovoid nodule measuring 2.5 cm in diameter. IpmaFmlilaoygpsdurt(eiarcnr:etachtec1aeyleltysmowplaoltietogohyxmyaolbofinurl-enpsedhioaicnsnintnsua,hcn×oldew4if0ilno0gec)lacytoeghdreacsneiuvnleatrcalclulyysttoeprslpaosemrf inpaehnoed-rImprint cytology of lesion showing cohesive clusters of neoplastic cells with abundant and finely granular cytoplasm and moderately pleomorphic nuclei located centrally or peripherally (a: haematoxylin- eosin, × 400). Neoplastic elements with abundant granular eosinophilic cytoplasm, large nuclei and evident nucleoli, are large, round or polyhedral cells arranged in solid sheets, islands and cords (d: haematoxylin-eosin, × 400). AfincdFtiyno:ilgtle×ucotulhsyup2ropmlg0eanor0sodas2m;urniitiranuiavtlciacctaerynylpliestfmooitbosmrnointaoudivnitnymietoi(ymkrane:feuora×onarc2pottai0lihnavl0pissta)htty,niaoccto-ciy1pbfht-eotearhdmnpienytlaiec(suaybhmlrt:yoasm×ltpu2iiolcnad0tfsa0yrimlni)tpsrdahsawinomtnidwtoaehnem(c)adbnartniamd- All tumour cells on immunohistochemical study showed finely granular immunoreactivity of the cytoplasm with antimitochondrial antibody (a: ×200), cytoplasmatic and membranous positivity for antikeratin antibody (b: ×200) and cytoplasmatic positivity for alpha-1-antichymotripsina (c and d: × 200; in c yet note neoplastic perineural infiltration). The cytoplasm of neoplastic cells seemed to be packed with numerous mitochondria These organuli were not clear, since their cristae appeared fragmented because of fixation in formalin solution without adjusted pH
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