A rare disease in an atypical location-Kimura's Disease of the upper extremity.

Kimura's disease is a rare chronic inflammatory disorder predominantly affecting young Asian male patients, occurring mainly in the head and neck regions. Kimura's disease of the upper extremity is extremely rare, and previous case reports in the literature show similar imaging characteristics with consistent location at the medial epitrochlear region, predominantly with unilateral involvement. We present the first reported case of Kimura's disease affecting the anterolateral aspect of the upper arm, sparing the medial epitrochlear region, illustrating that with typical MR appearance and serology, the involvement of this rare disease in an atypical location still warrants consideration of this diagnosis. There was also bilateral asymmetrical involvement in our patient, suggesting the possibility of a propensity for Kimura's disease affecting the upper extremities to have bilateral involvement, which may necessitate imaging of the clinically asymptomatic contralateral limb in these patients for early lesion identification and treatment.