said Isa An, MD of Dicle University, Diyarbakır, Turkey, and associates.
They described a 16-year-old Turkish girl who presented with an itchy rash on her back of 4 weeks’ duration. Treatment with oral antihistamines, and topical and systemic steroids were ineffective. On physical examination, there were erythematous macules, sporadic excoriated papules, and reticulate hyperpigmentation on her back. Complete blood count and liver function tests were normal.
Histopathologic examination showed “infrequent necrotic keratinocytes with marked acanthosis and spongiosis on the epidermis, increased basal layer pigmentation, and perivascular lymphocytic infiltrate on the upper dermis.” Because of these findings, a diagnosis of prurigo pigmentosa was made, they wrote in
Treatment with colchicine 1.5 g/day was started, and while the lesions resolved in the second week of treatment, the reticulate hyperpigmentation remained, Dr. An and her associates reported. The reticulate hyperpigmentation did not regress during the first month of treatment. At 6-month follow-up, there were no more symptoms of itch or recurrence of the original lesions. The reticulate hyperpigmentation was not treated.
A rare inflammatory skin disease seen principally in young Japanese women, prurigo pigmentosa has been reported in both men and women of other ethnicities, they said. Generally, macrolide antibiotics, such as clarithromycin, dapsone, and isotretinoin have been used effectively to treat prurigo pigmentosa. Minocycline and doxycycline are considered to be effective in treating this skin disease because of their anti-inflammatory effects and because they have “been shown to inhibit the synthesis of cytokines and chemokines that regulate leukocyte differentiation and activation.” Leukocyte differentiation and activation “are key pathologic features of prurigo pigmentosa,” the authors added.
Colchicine, a neutral, liposoluble tricyclic alkaloid, “exerts an anti-inflammatory effect by inhibiting neutrophil chemotaxis,” said Dr. An and her associates, which is why it is thought to be a potentially effective drug for treating prurigo pigmentosa, as shown in this case study. “Further studies are required to verify whether colchicine is an effective treatment option,” for prurigo pigmentosa, they added.
SOURCE: An I et al. Pediatr Dermatol. 2018 Apr 11.