The influence of clinical features mimicking primary immunodeficiency diseases (mPID) on children with Langerhans cell histiocytosis (LCH) - Four with mPID among 39 LCH children from one referral center during 18-year period

Comprehensive considerations for dermatologists: the application of FDG-PET in evaluating cutaneous lesions in pediatric Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a complex disorder characterized by the clonal proliferation of Langerhans cells, primarily affecting children and adolescents. This condition exhibits a wide spectrum of clinical presentations, necessitating a multidisciplinary approach for diagnosis, treatment, and follow-up. Cutaneous manifestations of LCH are significant, mimicking common dermatoses and posing diagnostic challenges. [18F]Fluorodeoxyglucose-Positron Emission Tomography (FDG-PET) has emerged as an important tool in the evaluation of pediatric LCH, offering insights into disease activity, extent, and therapeutic response. Moreover, FDG-PET provides a non-invasive means to distinguish between active LCH skin lesions and other dermatological conditions with similar clinical appearances, enhancing diagnostic accuracy and aiding in disease monitoring. This educational review summarizes the utility of nuclear imaging techniques, with a focus on PET scans, in the diagnosis and management of cutaneous pediatric LCH. A comprehensive literature search identified seven relevant articles, including retrospective studies and case reports. These studies highlight the efficacy of FDG-PET in localizing active LCH skin lesions, monitoring disease activity, and guiding treatment decisions. FDG-PET represents a valuable imaging modality for dermatologists, oncologists, and pediatricians managing pediatric LCH patients with cutaneous involvement. This non-invasive technique contributes to improved diagnostic accuracy and facilitates early intervention, ultimately enhancing patient care and outcomes.

Concomitant Langerhans and Interdigitating Reticulum Cell Hyperplasia in a Reactive Lymph Node of an Infant with Omenn Syndrome: A Diagnostic Pitfall for Langerhans Cell Histiocytosis

Omenn syndrome, a rare form of combined immunodeficiency in infants, presenting with recurrent infections, erythroderma, lymphadenopathy, hepatosplenomegaly, eosinophilia, and increased serum IgE levels. It is a fatal condition unless treated by hematopoietic stem cell transplant. Hence, an early diagnosis and a prompt treatment can lead to better outcome in these unfortunate babies afflicted with Omenn syndrome. Here, we present an 8-week-old infant with typical features of Omenn syndrome, both clinically as well as on laboratory analysis, but surprising immunohistochemical findings on lymph node biopsy.