A Case of Subcutaneous Sarcoidosis Occurring along the Superficial Veins of the Forearms: A Distinctive Cutaneous Manifestation Masquerading Venous Tropic Action in the Underlying Systemic Disease?

Sarcoidosis is a multisystem disease of unknown etiology, developing granulomas in any tissues and organs. Approximately 25% of sarcoidosis patients have cutaneous involvement with various clinical manifestations, which are categorized into specific or nonspecific diseases based on the histopathology; the former represents the typical sarcoid granulomas. Subcutaneous sarcoidosis is one of the specific skin lesions and often affects extremities, to a much lesser extent with other anatomical sites. Herein, we report the case of an 82-year-old Japanese man with subcutaneous sarcoidosis whose skin nodules exclusively overlay the lines of superficial veins on the forearms. This rare clinical presentation was discussed with the literature reported thus far to access the underlying disease pathophysiology from the viewpoint of tropic response to the venous system in systemic sarcoidosis.