Carotid body paraganglioma with prominent lymphocytic infiltration mimicking metastatic medullary thyroid carcinoma; A Case Report

Background: carotid body paraganglioma is a benign neuroendocrine neoplasm, presented usually as a single asymptomatic mass on mandibular region. Although on microscopic examination it has a typical zellballen pattern but duo to its prominent stromal alternations (such as sclerosing, lymphoplasmacytic, adenoma and angioma like), is a great emulator of other neoplasms in head and neck region especially metastatic tumors, so the definite diagnosis could be a challenge among pathologist .The most reported variant is sclerosing type and to the best of our knowledge the lymphoplasmacytic variant is so rare. In order to exclude other possibilities, the usage of immunohistochemistry is mandatory, which shows strong positive immunoreaction for chromogranin and synaptophysin . Surgical resection is the choice of treatment and in contraindication circumstances radiotherapy is replaced. Overally the tumor has a favorable clinical outcome. Case report: We report a rare case of carotid body paraganglioma presenting as a single asymptomatic mass of right mandibular region in a 45 year-old woman, with well-defined hypervascular mass on MRI .On surgery a resected well-circumscribed mass show tan nodular cut surfaces resembling lymphoid tissue, which composed of nests of cells with, granular eosinophilic cytoplasm embedded in a dense lymphoplasmacytic stroma containing few collagen bundles on micrpscopic examination. The neoplastic cells show diffuse positive immunoreaction for chromogranin and synaptophysin on IHC study. The 6 months follow up of the patient revealed no tumoral recurrence. Conclusion: This case indicate that although carotid body paraganglioma is a benign tumor with favorable behavior but because of its variable histologic features, (especially lymhoplasmacytic), stimulating other neoplasm and must be kept in mind in differential diagnosis of head and neck tumors with lymphocytic infiltration.

Keywords:

head and neck paraganglioma , carotid body tumor , paraganglioma