Rosai-Dorfman disease presenting as an isolated extranodal mass of the carotid sheath: a case report.

Rosai-Dorfman disease is a rare, benign granulomatous disease that typically presents with massive cervical lymphadenopathy. In less than 50% of cases, other soft-tissue manifestations may also be found in the head and neck. Rosai-Dorfman disease can be difficult to diagnose because of its rarity and its ability to mimic, both clinically and radiologically, more common diseases such as lymphoma. The histopathologic diagnosis can also be difficult to make, particularly when the disease exhibits extranodal manifestations. We present a case of isolated extranodal Rosai-Dorfman disease involving the carotid sheath, without the typical massive adenopathy.