Generalized Eruptive Histiocytosis or Juvenile Xanthogranuloma: A Clinicopathological Conundrum of Coexistence or Xanthomatization.

Diseases under the non-Langerhans cell histiocytosis (LCH) group often share clinical and histological similarities, making proper delineation highly challenging. A two-year-old female child presented with multiple, small raised asymptomatic lesions all over the body for one year. Cutaneous examination showed multiple brownish flat-topped and yellowish-brown dome-shaped papules scattered all over the body with hyperpigmented macules over the face. A provisional diagnosis of generalized eruptive histiocytosis (GEH) was made. But the dermoscopy and histopathological examination of flat-topped and dome-shaped papules showed features suggestive of generalized eruptive histiocytosis and juvenile xanthogranuloma (JXG) respectively, with a few overlapping features. Systemic examination was found to be normal. Hence an overlap of GEH and JXG was considered, with a thought of ongoing xanthomatization of GEH lesions. The transformation of GEH into xanthoma disseminatum, multicentric reticulohistiocytosis, progressive nodular histiocytosis, and juvenile xanthogranuloma (JXG) has been reported. It has also been reported that GEH and JXG, the two entities that belong to a continuous spectrum of histiocytoses with xanthogranulomatous pathology, can rarely co-exist in the same individual. The distinction between GEH and JXG is crucial, as they may require different management strategies. Our case stresses the fact that relying only on clinical diagnosis can be deceiving owing to the overlapping clinical, dermoscopic, and histopathological features of histiocytoses.