Acquired smooth muscle hamartoma with sebaceous component

Area of Science:

• Dermatology
• Pathology
• Medical Genetics

Background:

• Acquired smooth muscle hamartoma (ASMH) is a rare benign skin lesion.
• Characterized by hyperpigmented plaques, hypertrichosis, and follicular papules.
• Histologically, ASMH shows disorganized dermal smooth muscle bundles.

Observation:

• An 18-year-old male presented with a one-year history of unilateral facial hyperpigmentation and hypertrichosis.
• Clinical examination revealed a Blaschkoid plaque with hyperpigmentation, hypertrichosis, and papules.
• Histopathology demonstrated increased smooth muscle bundles, abundant sebaceous glands, and numerous hair follicles.

Findings:

• The case exhibited prominent sebaceous gland hyperplasia alongside smooth muscle hamartoma features.
• This presentation suggests a potential spectrum between ASMH and folliculosebaceous cystic hamartoma.
• The lesion combines histological characteristics of both hamartoma types.

Implications:

• This case expands the understanding of acquired smooth muscle hamartoma.
• It suggests a possible continuum of hamartomatous lesions involving smooth muscle and folliculosebaceous units.
• Further research may clarify the classification and pathogenesis of these rare conditions.