Granulation Tissue that Developed after a Minor Trauma in a Psoriatic Patient on Long‐term Etretinate Therapy

Synthetic analogues of retinoic acid, isotretinoin in particular, are known to cause granulation tissue in the nail sulcus and healing cystic acne. We observed granulation tissue that developed in a psoriatic patient on long‐term oral etretinate therapy (30 mg/day for 3 years), another synthetic analogue of retinoic acid. In August of 1988, the patient, a 44‐year‐old male, hit his lower leg against a wooden stick, resulting in a laceration. At that time he had relatively limited patches of psoriasis, but his skin was generally thin with teleangiectasia, even in areas without psoriasis, probably due to the long‐term use of oral etretinate and topical steroid. In spite of treatment with topical disinfectants and oral antibiotics, the wound progressed into granulation tissue surrounded by erythema and multiple punctate erosions with marked secretion of a clear exudate. The histological findings of the granulation tissue included the presence of proliferating microvessels and a relatively dense cell infiltration with a predominance of plasma cells on the sparse edematous connective tissue. Based on these findings, the rash was considered to be retinoid‐induced granulation tissue. As compared with previous reports, our case had the following characteristics: development of rash after minor trauma, rash on the lower leg, eosinophil infiltration into the rash. We believe that long‐term users of oral etretinate should be cautioned about the potential for delayed wound healing and the formation of granulation tissue.