A patient, aged 10 weeks, presented to the office. His parents complained of a rash on his scalp, axillae, and groin.
Clinically, the rash appeared to be seborrheic dermatitis, but the skin condition worsened after the infant underwent multiple treatments for seborrheic dermatitis six weeks prior.
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Langerhans cell histiocytosis (LCH) is a dysregulated proliferation of Langerhans cells, the antigen presenting cells of the skin and mucosa. Although LCH can affect a variety of different organs, the two most common sites are bone and skin.
LCH presents in a large spectrum of severity, ranging from asymptomatic to a very aggressive systemic disease. Other organs than can be affected include lymph nodes, lungs, thymus, liver, spleen, bone marrow, and the central nervous system.
LCH can occur in people across all ages; however, it is most commonly found in children aged 1 to 3 years. LCH can be congenital. Acute disseminated multisystem diseases are most commonly seen in children aged 3 years or younger.
LCH typically presents in the skin as 1 to 2 mm rose-yellow translucent papules, most commonly on the trunk and scalp. Mucous membranes and retroauricular, axillary, and genital folds also can be affected. These lesions are often scaled, and occasionally are crusted or ulcerated. Less commonly, LCH can present as nodules or pustules. LCH often presents similarly to eczema, miliaria, scabies, seborrheic dermatitis (as in this case), and varicella.
Historically, LCH was categorized into a number of different named diseases based on the severity of clinical findings. Hashimoto-Pritzker disease is the benign, self-limited form of LCH, and usually presents at birth or within the first few days of life.
Eosinophilic granuloma is another classification of LCH, characterized by localized, benign lesions. Hand-Schüller-Christian disease is a more chronic form of LCH, resulting in progressive, multifocal lesions.
Finally, Letterer-Siwe disease is a form of LCH most commonly found in newborns and infants that causes severe disseminated, multisystemic disease. If left untreated, Letter-Siwe disease will progress and become fatal.
The etiology of LCH is still largely unknown and poorly understood. Genetic factors, infectious agents (especially viral), and cellular and immune system dysfunction have all been correlated to an increased incidence of LCH. Furthermore, there is heavy debate on whether LCH is a reactive or neoplastic disease.
Some evidence supporting a reactive disease include the high differentiation of LCH cells, resemblance of the granulomatous lesions found in LCH to lesions found in foreign body reactions, and the spontaneous regression of these skin lesions. Many viruses have been postulated to be a key etiologic factor in this disease, but none have been proven to be directly responsible for it.
On the other hand, many characteristics of LCH implicate that disease may be a neoplastic disease. For instance, there are several familial cases of LCH and there is evidence of chromosome 7 instability and abnormal p53 protein in LCH.
Diagnosis is based on biopsy of either an osteolytic bone lesion or skin lesion. Langerhans cells are identified histologically based on their morphologic criteria and presence of CD1a and CD207 antigens. This is often a difficult disease to diagnose since it is a rare disorder, with only about three to five cases per million children and one to two cases per million in adults.
The prognosis for LCH is difficult to predict. Outcomes can range from localized self-limited forms to disseminated and even fatal cases. The main negative prognostic factors include onset before the age of 2 years, extent of the disease, purpura, and organ failure.
The diagnosis is commonly made by a dermatologist, but patients are then referred to oncology for treatment.
Aaron Fong is a medical student at Baylor College of Medicine. Adam Rees, MD, a graduate of the David Geffen School of Medicine at UCLA, practices dermatology in Los Angeles.
- Goldsmith LA et al. Fitzpatrick’s Dermatology in General Medicine. 6th ed. New York: McGraw-Hill; 2014.
- McClain KL. Clinical manifestations, pathologic features, and diagnosis of Langerhans cell histiocytosis. In: UpToDate, Rose, BD (Ed), UpToDate, Waltham, MA, 2014.