Granuloma annulare (GA) is a benign inflammatory skin disease¹. Here, we
report an atypical clinical presentation of localized GA associated with
cysts and open comedones.
An 85-year-old woman presented with a one-month history of asymptomatic
plaque on her right forearm. She had diabetes mellitus, hypertension and
dyslipidemia. Physical examination identified erythematous
well-demarcated and extensive plaque covered with multiple yellowish
papules from which a creamy liquid was easily expressed (figure 1A). We
noted, also, multiple open comedones located exclusively on the plaque,
filled with black keratotic plugs and associated with cribriform
scarring.
Histopathological examination of skin biopsy showed an area of
necrobiosis surrounded by histiocytes and lymphocytes in the mid dermis,
with some multinucleated giant cells (figure 1B and 1C). The diagnosis
of GA associated with cyst and open comedones was made.
GA is a benign dermatosis with variable clinical presentations. Some
triggering conditions were reported, especially, trauma, vaccination,
infections and sun exposure¹. Localized GA is the most commonly
recognized presentation and lesions are usually concentrated on the
extremities. The finding of milia, cysts and open comedones over the
lesions of GA is extremely rare, with only three previous reports in the
literature². Cysts and open comedones, which are formed by dilated
pilosebaceous follicles filled with laminated keratinous material, may
be explained by collagen and elastic fibrer damage observed in actinic
GA².