Cutaneous histiocytoses: a clinical and histopathological series of 25 cases

Cutaneous histiocytoses are a heterogeneous group of disorders characterized by histiocytic proliferation within the skin, broadly classified into Langerhans cell histiocytosis (LCH) and non-Langerhans cell histiocytosis (non-LCH). The clinical presentation varies widely, making histopathological and immunohistochemical analyses essential for accurate diagnosis. This study aims to evaluate the clinical, histopathological, and immunohistochemical features of patients diagnosed with cutaneous histiocytosis in a single-center cohort. We retrospectively analyzed 25 patients diagnosed with cutaneous histiocytosis between 2000 and 2022. Demographic characteristics, clinical presentation, lesion distribution, systemic involvement, histopathology, and immunohistochemical findings were assessed. Statistical analyses were performed using IBM SPSS Statistics 21.0. Of the 25 patients, 19 were diagnosed with LCH and 6 with non-LCH. The median age was 7 years (Q1-Q3: 2–29 years), and the median symptom duration was 4.5 months (Q1-Q3: 2–12 months). The most common LCH presentation was seborrheic dermatitis-like lesions (9/19 patients), predominantly on the scalp, with CD1a (+) and Langerin (+) histiocytic infiltration. Among non-LCH cases, three were juvenile xanthogranuloma (JXG), one was generalized eruptive histiocytosis (GEH), one was Erdheim-Chester disease (ECD), and and one was unclassified non-LCH. Systemic disease was observed in 28% of patients (7/25), including hepatosplenomegaly (3 patients), lytic bone lesions (3 patients), and pontine lesions with lung cysts (1 patient). This study underscores the diverse clinical and histopathological spectrum of cutaneous histiocytoses, emphasizing the importance of immunohistochemistry in distinguishing LCH from non-LCH subtypes. The high frequency of seborrheic dermatitis-like lesions in LCH suggests that persistent or treatment-resistant cases should prompt histopathological evaluation.