Clinical presentations of the most common histiocytic disorders

Histiocytic diseases are significantly rarer than diseases derived from lymphocytic, plasmacytic, or myeloid lineages, and thus are encountered infrequently in hematology and oncology clinics. The most common form is Langerhans cell histiocytosis, which in adults has an incidence of 1-2 cases per 1 million; the others are considerably rarer, with their occurrence reported only by the number of described cases rather than through incidence or prevalence. Their rarity leads to delays in establishing an accurate diagnosis.

The group of histiocytic diseases includes seven clinical units: Langerhans cell histiocytosis, indeterminate dendritic cell histiocytosis, diseases from the juvenile xanthogranuloma group, Erdheim-Chester disease, Rosai-Dorfman disease, ALK-positive histiocytosis, and histiocytic sarcoma. Each of the described diseases has specific manifestations that distinguish it from the manifestations of other malignant blood disorders. The aim of this article is to remind the reader of these manifestations through images and text, thereby contributing to the timely recognition of these rare diseases.

Treatment procedures are rapidly evolving, but the clinical presentations of these diseases remain unchanged. The disease profiles presented in this publication should aid in their early diagnosis and consequently in timely treatment.