Accidental PUVA burns, vitiligo and atopic diathesis resulting in prurigo\nnodularis: a logical but undocumented rarity
A 50-year-old woman presented to this clinic with severely pruritic nodules and plaques\non her legs and breasts. She developed vitiligo at the age of 18 years and had been\nunsuccessfully treated with many drugs. In 1991, she was treated with home psoralen plus\nultraviolet-A radiation (PUVA), using 20 mg of oral methoxsalen. The light source used\nwas a set of 4 tube lights of 100W, emitting UVA with wavelengths between 315 and 350\nnm, and she exposed the affected areas for three minutes three times a week. Within\nabout 5 months, there was marked improvement of the vitiligo lesions on her legs and\nalso total clearing of the lesions on her face, except for the ones on the lips. Around\nthis time, she accidentally fell asleep during her PUVA sessions and woke up 60 minutes\nlater with blistering burns on her breasts and legs, which took a month to heal. During\nthe healing stage, she started developing thickened skin, nodules and plaques on her\nlegs and breasts, which were intensely itchy. She was given emollients, topical\nsteroids, antihistamines, individually and in combination, with little benefit. Many\nnodules coalesced to form scaly plaques. Then, her homeopath husband started treating\nher with some homeopathic medication, which apparently caused resolution of the lesions\nfor many years. The lesions only reappeared in 2004. Several physicians and\ndermatologists diagnosed her condition as psoriasis and post-burn keloids. She was\nprescribed oral steroids by a private practitioner for a few months, which was later\nstopped as she developed diabetes. She now has excruciating itching, which has severely\naffected her quality of life.\nOn examination, she had vitiligo on her breasts and lower limbs, showing perifollicular\npigmentation. Her legs were studded with thick, horny, hyperkeratotic nodules with a\nrough surface, many of them coalescing to form plaques on the anterior aspect (). She had severely pruritic erythematous\nnodules on the breasts (). The skin on her\nface, abdomen, back and upper limbs was normal. She was diabetic, hypothyroid and took\nmetformin and thyroxine daily. Her blood work up and serum chemistry were normal, except\nfor an IgE level of 700 IU/ml, with no history, signs or symptoms of atopy such as\nchronic itching, eczema, allergic rhinitis or asthma. She, however, had a family history\nof eczema and allergic rhinitis. A skin biopsy taken from the nodule showed a\nsuperficial perivascular lymphocytic infiltrate with moderate irregular epidermal\nhyperplasia. The papillary dermis was thickened with papillomatosis and showed thickened\nbundles of collagen in a vertical array. The capillaries in the papillary dermis were\nincreased in number and thick-walled. The granular layer was thickened and the stratum\ncorneum showed marked compact orthokeratosis (). One of the sections showed abundant deposit of amyloid in the papillary\ndermis. The histological diagnosis was prurigo nodularis (PN) associated with lichen\namyloidosis (). We started her on 900 mg\nof gabapentin with topical halobetasol and petrolatum, and she reported a relief of\nabout 20% of her itching in 30 days.