Granulation tissue proliferation during isotretinoin treatment.

Excessive, pseudotumoral granulation tissue proliferations appeared in three patients receiving isotretinoin for nodulocystic acne. A review of the literature disclosed few reports of this unusual adverse reaction. Two clinical patterns have been reported; one in a periungual location and the other occurring in the sites of acne lesions during isotretinoin therapy. Loose edematous connective tissue with small vessels and chronic inflammatory infiltrate were the histologic findings in all three cases.