Aseptic and alopecic nodules of the scalp - Hair and Scalp
AANS predominantly affects young males between 20 and 30 years of age. The nodules are firm or fluctuant and most are asymptomatic, but patients may have mild pruritus, pain, or discomfort. Nodules vary in size from 1.5-3 cm.
The etiology of AANS has not been studied. The current hypothesis suggests that nodule formation may be attributed to an immunological-driven granulomatous reaction to a foreign body or follicular disruption that occludes the follicle. The granulomatous infiltrate is located deep in the hair follicle and is likely responsible for nonscarring alopecia.
L98.9 – Disorder of the skin and subcutaneous tissue, unspecified
10684951000119100 – Nodule of subcutaneous tissue of head
238725004 – Non-scarring alopecia
- Dissecting cellulitis of the scalp (DCS) – DCS is a scarring alopecia. Ultrasound shows fluid collections and abscesses within hypoechoic fistulous tracts that reach the hair bulb.
- Trichilemmal cyst (TC) – TC forms smooth, firm nodules between the shaft and bulb of the follicle, with hair loss. The histology shows an absent granular layer in the cystic wall with an abrupt transition from stratum spinosum and keratin. Cysts contain keratin debris or cholesterol crystals. Ultrasound shows multiple compact lamellae of keratin debris inside the epidermoid cyst, forming an onion ring pattern with alternating hypoechoic and hyperechoic concentric rings.
- Pilar cyst
- Epidermal cyst
- Proliferating trichilemmal tumor
- Folliculitis decalvans
- Alopecia areata
- Tinea capitis
- Aplasia cutis congenita
- Keratinocytic or sebaceous nevi
- Cutaneous metastases
- Lipedematous scalp