A 52-year-old man presented to his primary care physician complaining of a painless mass in the left elbow that had slowly enlarged over a 2-year period. When pressure was applied to the mass, the patient experienced "electrical shocks" that radiated to the left hand.Physical examination demonstrated a soft, mobile mass in the anteromedial aspect of the left antecubital fossa. The patient's strength, motion, sensation, and two-point discrimination were normal. A Tinel test was positive, evoking pain and numbness within the left forearm and hand. Nerve conduction velocity studies were normal. Imaging FindingsRadiography of the left elbow revealed soft-tissue prominence in the antecubital fossa (Fig 1). No osseous erosion was present. Magnetic resonance (MR) imaging of the left elbow verified a round, sharply marginated intermuscular mass measuring 5.4 cm in diameter. The mass was in the antecubital fossa, on the ulnar side of the elbow joint line. On spin-echo T1-weighted MR images, the lesion was homogeneous and isointense relative to skeletal muscle (Fig 2). The median nerve was identified as a distinct structure at the proximal and distal aspects of the mass; however, it could

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A wide variety of superficial soft-tissue masses may be seen in clinical practice, but a systematic approach can help achieve a definitive diagnosis or limit a differential diagnosis. Superficial soft-tissue masses can generally be categorized as mesenchymal tumors, skin appendage lesions, metastatic tumors, other tumors and tumorlike lesions, or inflammatory lesions. With regard to their imaging features, these masses may be further divided into lesions that arise in association with the epidermis or dermis (cutaneous lesions), lesions that arise within the substance of the subcutaneous adipose tissue, or lesions that arise in intimate association with the fascia overlying the muscle. The differential diagnosis may be limited further by considering the age of the patient, anatomic location of the lesion, salient imaging features, and clinical manifestations.

Cherubism is a rare osseous disorder of children and adolescents. Although the radiologic characteristics of cherubism are not pathognomonic, the diagnosis is strongly suggested by bilateral relatively symmetric jaw involvement that is limited to the maxilla and mandible. Imaging typically shows expansile remodeling of the involved bones, thinning of the cortexes, and multilocular radiolucencies with a coarse trabecular pattern.

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