Cutaneous Leiomyoma Mimicking a Keloid.

Area of Science:

• Dermatology
• Oncology

Background:

• Cutaneous leiomyomas (CL) are rare, benign smooth muscle tumors of the skin.
• Three subtypes exist: piloleiomyoma, genital leiomyoma, and angioleiomyoma, with piloleiomyoma being the most common.
• Piloleiomyomas typically present as painful papulonodules on the trunk and extremities.

Observation:

• A 30-year-old woman presented with numerous painless, itchy, red-brown papules on her gluteal region, appearing after intramuscular injections.
• Clinical examination revealed grouped papulonodules resembling keloids.
• Histopathologic examination confirmed neoplastic infiltration with smooth muscle cells, positive for actin and caldesmon.

Findings:

• The patient was diagnosed with pilar leiomyoma, a subtype of cutaneous leiomyoma.
• This case presented atypically as painless, itchy lesions in an unusual location, mimicking keloids.
• Histopathology is crucial for differentiating CL from other papulonodular lesions like keloids.

Implications:

• Cutaneous leiomyomas, particularly piloleiomyomas, should be considered in the differential diagnosis of keloid-like lesions, especially when treatment-resistant or in atypical locations.
• Accurate diagnosis relies on histopathologic examination, identifying characteristic smooth muscle cell bundles and positive smooth muscle markers.
• While solitary lesions are often sporadic, multiple lesions may indicate hereditary syndromes, necessitating further investigation.