Patients who seek dermatology care may often present with skin conditions that may present a clinical diagnostic dilemma. The skin condition may not have the hallmark features of a classic dermatologic condition, or the patient may present with skin findings that may be seen in several different and unique dermatologic entities. This column will present the case of a patient who presents with a pruritic skin rash that both clinically and histiologically could represent either histiocytosis or mastocytosis. The patient’s clinical course, along with a review of both complex dermatologic conditions will be presented. A histiological discussion will also provide a closer examination of the disparities and similarities of the conditions utilizing information gleaned from the biopsy specimens.