Incidence of xeroderma pigmentosum in Larkana, Pakistan: a 7-year study.

Xeroderma pigmentosum (XP) is a rare autosomal recessive inherited disorder caused by a defect in the normal repair of DNA of various cutaneous cell types damaged by exposure to ultraviolet radiation. We present our 7-year experience with 36 XP patients who either visited the Department of Dermatology or were seen in the medical camps arranged in remote areas for patients' welfare, from 1995 to 2001. For ease of discussion we classified all cases into the following subgroups on clinical grounds only: mild, those with light brown freckles on the face alone; moderate, those with dark brown freckles with burning on the face, neck, ears, chest, hands and photophobia but without other associated obvious cutaneous and ocular changes; severe, those with extensive dark brown freckles with burning on the exposed parts as well as on the unexposed parts of the body, i.e. the chest, back, abdomen and arms including other associated cutaneous and ocular changes such as ulcers and malignancy. Of 36 patients, three (8.3%) were classified as mild, nine (25%) moderate and 24 (66.7%) severe; there were 18 males and 18 females, age range 2-30 years (mean 8.9 years). Seventeen patients had cutaneous changes: actinic keratosis, keratoacanthoma, fissures and ulcerative nodules on the exposed parts of the body. Four patients had wide ulcers, along with mass formation and severe pigmentation on the face, neck and head. Twenty-nine patients developed ocular symptoms: photophobia, conjunctivitis, corneal keratitis and lid ulcer. One patient had complete loss of vision. Histopathological findings revealed that six patients had squamous cell carcinoma (SCC) on the face, head, ear or lip. More than one sibling (two to four) was affected in four families. The majority of cases (20/36, 55.6%) were from the Brohi tribe (skin type III), while the remaining cases (16/36, 44.4%) were from the Sindhi population (skin type IV). The large number of XP patients seen in those with skin type III (Brohi tribe) compared with skin type IV (Sindhi population) indicates that the skin type and the race has a considerable value in the pathogenesis of XP. Furthermore, 24 of 36 patients were in the severe group and six of these had SCC. Moreover, no neurological abnormalities were observed in our patients. All patients were treated according to disease severity by prescribing oral antibiotics, local steroids, sunscreens and/or chemotherapy followed by irradiation in malignant cases. Two patients died because of extensive SCC.