Retrograde differential diagnosis of carcinoma and pleomorphic adenoma of ectopic tissue of the salivary gland

BACKGROUND: The differential diagnosis of malignant neoplasms in the neck presents significant difficulties in terms of detecting a primary organ tumor and an extraorgan primary lesion. It is especially difficult to identify it in the presence of enlarged regional metastatic lymph nodes located actually on the border with the primary localization of the tumor. In salivary gland tumors, even modern radiological and morphological diagnostic capabilities do not always allow for clear differentiation of organ specificity, categories of benign or malignant, as well as distinguishing the primary tumor from the metastatic process.

DESCRIPTION OF CLINICAL CASE: In a patient with obvious clinical signs of nodular thyroid lesion, a malignant process was cytologically excluded after the initial visit to the polyclinic. However, an additional examination revealed a tumor pathology of the upper third of the neck, which did not confirm its organ specificity to large salivary glands and regional lymph nodes according to combined data from modern methods of radiation diagnostics. The results of cytological diagnosis of several tumor-like neoplasms on the neck contributed to the radical treatment of head and neck tumors in the surgical department with routine histological and immunohistochemical examination. Morphologically confirmed malignant genesis from salivary gland tissue without organ specificity showed different histological conclusions. In the absence of a recurrence of the disease, taking into account contradictory morphological conclusions, the hospital conducted a review of histological scans of the immunohistochemical examination of the tumor in the reference center. The revision confirmed the presence of pleomorphic adenoma of aberrant salivary glands in the retrograde diagnosis variant.

CONCLUSIONS: A clinical observation is presented in which only the results of control immunohistochemical study allowed formulating the final clinical and pathological diagnosis of pleomorphic adenoma of the ectopic salivary gland with a multicentric growth pattern in the variant of retrograde differential diagnostics with different forms of carcinoma.