السلام عليكم ورحمة الله وبركاته
تحية طيبة وسلام إلى جميع أطباء الجلد العراقيين والعرب الأعزاء
Eruptive Vellus Hair Cysts (EVHC)
1. Definition
Eruptive vellus hair cysts (EVHC) are rare, benign follicular cysts containing vellus hair shafts. They typically present as multiple small papules, most commonly on the central chest, particularly over the sternum.
2. Vellus Hair
Vellus hairs are fine, short, and usually lightly pigmented or blond hairs normally present on the face, trunk, and extremities. They differ from terminal hairs, which are longer, thicker, and more heavily pigmented and are mainly found on the scalp, beard, axillae, and pubic region.
3. Epidemiology
Familial cases usually present during early childhood, whereas sporadic cases tend to develop during adolescence. Males and females are affected approximately equally. Most cases occur as an isolated skin disorder.
Associated Disorders
EVHC may occasionally occur in association with:
Steatocystoma multiplex
Pachyonychia congenita
Anhidrotic ectodermal dysplasia
Hidrotic ectodermal dysplasia
4. Pathogenesis
The proposed pathogenic sequence is:
Infundibular occlusion
Cystic dilatation of the hair follicle
Secondary atrophy of the hair bulb
Formation of a cyst containing vellus hair shafts
EVHC is therefore thought to represent a developmental abnormality of the pilosebaceous unit. Familial cases may show autosomal-dominant inheritance and may be associated with mutations in keratin genes, particularly KRT17, which encodes keratin 17.
5. Clinical Features
Typical lesions are:
Small, 2–3 mm papules
Smooth and dome-shaped
Red-brown or skin-colored
Usually located over the sternum/central chest
May occur on the extremities or vulva
May be solitary, few, or numerous, occasionally numbering in the hundreds
Some lesions may be umbilicated or dimpled
Occasionally have a scaly or crusted surface
6. Differential Diagnosis
Condition Typical Clinical Clue
Eruptive vellus hair cysts Small papules on the central chest containing vellus hairs
Steatocystoma multiplex Multiple larger yellowish or skin-colored cysts
Milia Small white, keratin-filled papules
Comedones Follicular opening with a keratin plug
Folliculitis Inflammatory papules or pustules
Epidermoid cysts Usually larger lesions, often with a punctum
7. Diagnosis
Diagnosis is often made clinically, based on the combination of:
Typical age + characteristic morphology + typical distribution
Examination of Cyst Contents
Incision or puncture of a lesion may reveal vellus hair shafts within the cyst.
Histopathology
The characteristic histopathological findings include:
A cyst lined by stratified squamous epithelium
A granular layer
A cystic cavity containing laminated keratin
Variable numbers of vellus hair shafts
Classic Histological Concept
Squamous epithelial-lined cyst + laminated keratin + vellus hair shafts = EVHC
8. Treatment
Because EVHC is benign and often asymptomatic, treatment is frequently unnecessary.
Conservative Management
Reassurance
Observation
Spontaneous resolution occurs in approximately 25% of children.
Medical Treatment
Various therapies have been attempted, although results are generally limited or inconsistent:
Urea-containing keratolytics
Salicylic acid
Topical tretinoin
Oral isotretinoin
Oral acitretin
Procedural Treatment
Individual lesions may be treated with:
Excision
Curettage
Cryotherapy
Laser
However, procedural treatment should be considered carefully because it may result in scarring, particularly when numerous lesions are present.
الأجابات الصحيحة الأطباء الاختصاص
1.د. زينب حافظ
استشارية الأمراض الجلدية
م. الرمادي التعليمي
2.د.كريمة امين طب بابل
3.د.أحمد عبد عيسى أخصائي الجلدية دائرة صحة كركوك
الأجابات الصحيحة طلاب الدراسات العليا
ايناس عبد القهار
بورد عراقي / مركز تدريب الرمادي
الأستاذ الدكتور
خليفة الشرقي
