Painless Forearm Mass Noted During Exercise

Case at a Glance

A 30-year-old male presented with a painless, mobile mass on his forearm that became prominent during muscle contraction and exercise activities.

Patient's Story

The patient, a physically active 30-year-old male (height 5'11", weight 220 lbs), noticed an unusual protrusion on his forearm while performing bicep curl exercises at the gym. He reported that the mass becomes visible and palpable when his arm is extended or flexed, particularly when the wrist is actively engaged. The patient emphasized that the lesion is completely asymptomatic - causing no pain, discomfort, or functional limitations. He described the mass as having a fixed anatomical location but noted that it can be temporarily displaced with direct manual pressure, after which it returns to its original position.

Initial Assessment

Physical examination revealed a soft tissue mass on the forearm that became prominent with muscle activation. The lesion was non-tender to palpation, mobile, and appeared to be related to underlying muscle or fascial structures. No overlying skin changes, erythema, or warmth were noted. The mass demonstrated characteristic behavior of appearing with muscle contraction and becoming less prominent at rest.

The Diagnostic Journey

Given the presentation of a mass that became prominent with muscle contraction and the patient's athletic background, differential diagnoses included soft tissue tumors, lipomas, muscle herniation, and fascial defects. The key clinical features - painless nature, relationship to muscle activity, and ability to reduce with pressure - pointed toward a specific diagnostic consideration.

Final Diagnosis

Based on clinical presentation and expert consultation, the working diagnosis was transfascial muscular herniation. This condition occurs when muscle tissue protrudes through a defect in the overlying fascia, typically becoming more prominent during muscle contraction or increased compartment pressure during exercise.

Treatment Plan

Conservative management was initially recommended given the asymptomatic nature of the condition. Patient education regarding the benign nature of muscle herniation was provided. Monitoring for any changes in size, symptoms, or functional impairment was advised. Surgical repair could be considered if the patient developed pain, functional limitations, or cosmetic concerns in the future.

Outcome and Follow-up

The patient was reassured about the benign nature of the condition and advised to monitor for any changes. Regular follow-up was scheduled to assess for progression or development of symptoms that might warrant surgical intervention.