Hair cortex comedo: a series of 34 cases

Area of Science:

• Dermatopathology
• Histopathology
• Cutaneous Oncology

Background:

• Hair cortex comedo is a rare, comedo-like clinical lesion.
• Originally described in 2 cases, its histological features include a keratinous plug resembling hair cortex.
• Previous understanding suggested it might be a variant of dilated pore of Winer.

Purpose of the Study:

• To characterize the clinical and histopathological features of hair cortex comedo.
• To investigate the origin of hair cortex comedo based on a larger case series.
• To differentiate hair cortex comedo from other similar-appearing skin lesions.

Main Methods:

• Retrospective and prospective collection of 34 cases of hair cortex comedo.
• Clinical description of lesion characteristics, including age, sex, location, and appearance.
• Detailed histopathological examination of lesion morphology, cellular composition, and associated inflammatory infiltrate.

Main Results:

• A series of 34 cases showed a slight female predominance (1:1.4) with a mean age of 28.8 years.
• Lesions were solitary, predominantly on the head, neck, or trunk, appearing as blue subcutaneous papules/nodules.
• Histopathology revealed a vertically oriented plug of laminated corneocytes, often with entrapped melanin, shadow cells, calcification, and granulomatous inflammation.

Conclusions:

• Hair cortex comedo presents distinct histopathological features, including a laminated corneocyte plug and granulomatous inflammation.
• The presence of matrical or supramatrical epithelium suggests these cells are the likely origin.
• Hair cortex comedo is likely a distinct entity, not merely a variant of dilated pore of Winer.