Comedonal granuloma annulare

A 56-year aged female presented to us with erythematous lesions on forearms for 3 years. Physical examination showed erythematous papules and plaques on extensor surface of forearms. The largest plaque had raised borders studded with open comedones [Figure 1]. All routine investigations were normal. Dermoscopy showed blurry vessels over a pinkish-red background, yellowish-orange structureless areas, and open comedones filled with keratotic plugs [Figure 2].

Close

Figure 1:

Erythematous papules and annular plaques with open comedones overlying the largest plaque.

Export to PPT

Close

Figure 2:

Dermoscopy showing blurry vessels over a pinkish-red background, yellowish-orange structureless areas, and open comedones filled with keratotic plugs (Dermlite DL4, ×10).

Export to PPT

Skin biopsy showed a palisading granuloma in reticular dermis around focus of fibrin and mucin deposition and incomplete collagen degeneration. Dilated follicular infundibulum filled with keratinous material corresponding to a comedo was seen [Figure 3].

Close

Figure 3:

Palisading granuloma around focus of fibrin and mucin deposition and incomplete collagen degeneration. Dilated follicular infundibulum filled with keratinous material is seen adjacent to the granuloma (H&E, 200×).

Export to PPT

Degeneration of collagen and elastin is a hallmark histological feature of granuloma annulare. Loss of dermal support induces distension of infundibular canal of sebaceous follicle resulting in open comedones overlying lesions of granuloma annulare.^[1] Comedonal granuloma annulare should be differentiated from perforating granuloma annulare, actinic comedonal plaque, granuloma multiforme, and annular elastolytic giant cell granuloma.