Adult onset atopic dermatitis with secondary follicular mucinosis with cyclosporine induced spiny follicular hyperkeratosis and hair casts

Secondary follicular mucinosis developing in adult patient with atopic dermatitis (AD) was observed on histology. Due to severity of disease, patient was started on oral cyclosporine 300 mg daily in 3 divided doses. Two weeks later patient started developing multiple spiny follicular keratoses mainly on face but also on extremities and trunk along with hair casts on scalp. Repeat biopsy from such keratotic lesions confirmed diagnosis spiny follicular hyperkeratosis (SFH). On investigations no evidence of multiple myeloma or any other malignancy was found. Cyclosporine was stopped and lesions cleared over 2 weeks. We report this case due to rare association of AD with follicular mucinosis and cyclosporine induced SFH with hair casts.