Psoriasis and Type 1 Diabetes Mellitus

These pruritic but otherwise asymptomatic lesions on the right upper arm of a 77-year-old woman first appeared about 1 year before she sought medical consultation. The patient's history included frequent, generalized pruritus, which was believed to be secondary to long-standing type 1 diabetes mellitus.

Robert P. Blereau, MD of Morgan City, La, noted that the affected area showed streaking of hyperkeratotic lesions at an angle that would be consistent with the patient scratching her skin with the opposite hand. These lesions are indicative of Koebner's phenomenon-psoriatic eruptions that occur at sites of injury or trauma.

The microscopic pathologic differential diagnosis included guttate psoriasis, confluent and reticulate papillomatosis, acanthosis nigricans, and multiple seborrheic keratoses. A biopsy of material from a lesion was consistent with guttate psoriasis, a condition that is often seen in children, particularly those who have had a recent streptococcal infection or viral upper respiratory tract disease.

Therapies for psoriasis include topical corticosteroids, topical vitamin D derivatives, and anthralin. This patient refused treatment.