Neutrophilic eccrine hidradenitis: A new culprit-carbamazepine
A 40-year-old woman was admitted in the medical ward with complaints of fever, puffiness of face, vomiting and skin rash since five days. She was a known case of epilepsy and was taking carbamazepine for the same for the past one month. A provisional diagnosis of carbamazepine syndrome was made and the patient was referred to the dermatology department.\nGeneral physical examination showed the patient to be febrile and her vital parameters were within normal limits. No other abnormalities were noted. The dermatological examination showed multiple dry, non scaly, discretely arranged, round to oval, bilaterally near symmetrical papules, nodules, vesicles and pustules over the forearms and hands []. Mild peeling of skin was seen over the abdomen, proximal upper and lower limbs. Mucosa, scalp, nails and genitalia were normal.\nClinically, the differential diagnosis included toxic epidermal necrolysis, acute febrile neutrophilic dermatosis, bullous pemphigoid and DRESS syndrome. Extensive evaluation found no infectious focus. Complete blood count, biochemical parameters and urine analysis were normal. Nikolsky's sign and pathergy test were negative. Tzanck test was negative. A skin biopsy of the cutaneous lesions over the right forearm was performed. Histological features of the biopsy consisted of a neutrophilic infiltrate surrounding the eccrine glands and sparing the duct. There was a focal interface vacuolar dermatitis. An ill-defined collection of histiocytes, large and pleomorphic, and scattered lymphocytes could be observed within the dermis []. Special stains were negative. Based on the clinical and histological findings, a diagnosis of NEH secondary to carbamazepine was made. Opinion with an oncologist was sought and basic screening for malignancies did not reveal any evidence of malignancy. Oral corticosteroids were initiated in tapering doses. The fever subsided over the next three days and the skin lesions resolved gradually with post-inflammatory hyperpigmentation.\nIn view of the condition starting a few weeks after initiation of carbamazepine, resolution on stopping carbamazepine, and response to steroids, a final diagnosis of NEH secondary to carbamazepine was made. Detailed history did not reveal any other drug being taken by the patient in the last six weeks. Causality assessment score was performed using Naranjo's algorithm and was scored 6 which suggested a probable relationship between the reaction and carbamazepine. Re-challenge to carbamazepine was not performed as the patient was put on a different class of anti-epileptic drugs.