By Gary M. White, MD
Courtesy Michael O. Murphy, MD
Langerhans cell histiocytosis (LCH)--formerly called histiocytosis X--is a rare skin condition of infants that results from a clonal proliferation of Langerhans cells.
LCH in an infant may present as a red, scaly, seborrheic dermatitis-like rash of the scalp. On the skin, multiple tan or flesh-colored papules may be seen. These often heal with small scars. There may be an intertrigo-like rash of the flexures, e.g., in the diaper area. Purpuric lesions may occur. Internal manifestations include bony defects of the skull, diabetes insipidus, and granulomas of the bones (or skin).
LCH in an adult may present as an intertriginous rash of the groin, axilla and inframammary areas. Vulvar LCH in a female adolescent may present as pain, pruritus, dyspareunia, burning, discharge diffuse erythema, scattered erosions, superficial ulcerations, papules on the mucosal surface of the labia majora, thickening of the labial minora with partial detachment [PD 2017;34;485].
Workup should be carried out by an expert in LCH. In the past, HP (including ear exam to exclude otitis and abdominal exam to exclude hepatosplenomegaly), skin biopsy, CBC, LFT's, creatinine, skeletal survey (e.g., of the skull, long bones, and thorax), bone marrow biopsy, CAT scan of the body, and MRI of the hypothalamic region have been performed.
The evaluation and management ideally should be carried out by someone experienced with this disease. Mild disease may remit after 1-3 months so a period of observation may be appropriate (see congenital self-healing reticulohistiocytosis). For cutaneous disease only, potent topical steroids are the usual first-line treatment. Tacrolimus, imiquimod, nitrogen mustard, and UVB or PUVA have been employed as well.
For persistent or widespread disease, therapies which have been used include prednisone, methotrexate, thalidomide, radiation therapy, and chemotherapy. Etoposide, a semisynthetic derivative of podophyllotoxin, has been effective in both children and adults. Thalidomide (100 mg/day followed by 50/d) has been used effectively in adults.
Activating BRAF V600E mutations have been found in patients with Langerhans cell histiocytosis and may help direct therapy. Indeed vemurafenib has been suggested as first-line therapy in BRAF-mutated Langerhans cell histiocytosis [JAAD July 2015 Volume 73, Issue 1, Pages e29–e30].
Spontaneous resolution of skin lesions may be followed by relapse, e.g., bony lesion at 6 months of age, diabetes insipidus at 4 years of age, cutaneous relapse at 3 months, scalp nodule at 3 years. Thus, long-term followup is recommended.
Courtesy Michael O. Murphy, MD
Small papules and crusted papules may be seen.
A 2-year-old boy with a 1-month history of asymptomatic changes in most of the fingernails, fever, weight loss, and fatigue. Cutaneous examination revealed yellowish greasy scales and crusts over the scalp and a small number of purpuric papules over the trunk, feet, arms, and legs. Dermatology Online Journal 22(7)