Unusual presentations of adenoid cystic carcinoma in extra-salivary gland subsites in head and neck region: a case series.

Adenoid cystic carcinoma (ACC) is an uncommon malignant epithelial tumor occurring in head neck region, accounting for approximately 10% of all salivary gland neoplasms. Extra-salivary gland involvement of other head neck subsites by ACC may present in unusual modes creating clinical dilemma. Here we present some cases with extra-salivary gland ACC. In this series six cases with extra-salivary gland ACC were included. Three patients presented with external auditory canal and temporo-mastoid region involvement of whom two cases also had intracranial extension. In one case tongue was the site of involvement where it was confused with benign neurogenic tumour. Palatal erosion with formation of oro-nasal fistula was the the manifestation of ACC involving palate. On the other hand sinonasal bleeding mass which came out as ACC on histopathological examination did not cause any palatal erosion and was removed successfully via lateral rhiniotomy. In all these cases patients were treated with post-operative radiotherapy and were closely followed up for early detection of any distant metastasis. The experience about the various unusual manifestations of ACC and the therapeutic challenge poised by the cases is discussed here.