Hybrid salivary gland tumor of the upper lip or just an adenoid cystic carcinoma? Case report

A 65 year-old male patient with a one year-duration tumoral growth located in the upper lip was diagnosed on incisional biopsy as epithelial-myoepithelial carcinoma. After wide surgical excision the histopathological analysis revealed the lesion was composed predominantly (>90%) of adenoid cystic carcinoma. In new sections it was found a very small and isolated area of adenoid cystic carcinoma at the bottom of the incisional biopsy. As surgical margins were free of lesion, no adjuvant treatment was given. The occurrence of a transitory ischaemic attack at 36 months of follow-up led to a neurological and MRI evaluation, which disclosed a well-defined 3.5x3 cm lesion suggestive of metastasis, located on the right temporal area. The lesion was surgically removed and a histopathological diagnosis of neurocysticercosis was rendered. After 40 months of follow-up there is no evidence of recurrence. Conclusion: True hybrid tumors of salivary glands are rare and treatment in each case should be done according to the component with the higher aggressiveness. However, the occurrence of epithelial-myoepithelial carcinoma areas within an adenoid cystic carcinoma seems to be a frequent finding, and because both lesions share a common origin, some authors consider that this may not be a true hybrid neoplasm but a variant of the latter.