Clinical Presentation

A 4-year-old girl presents with back pain.

Figure 101A

Figure 101B

Radiologic Findings

Langerhans’ cell histiocytosis (LCH)

Differential Diagnosis

• Leukemia
  
• Hodgkin’s lymphoma
  
• Metastatic disease: neuroblastoma
  
• Hemangioma
  
• Osteopenia: steroid treatment
  
• Gaucher’s disease

Discussion

Background

LCH is a spectrum of disease processes resulting from the abnormal clonal proliferation of the Langerhans’ cell histiocyte (and its precursors), and the resultant infiltration of these cells into normal tissues. Bone, skin, and lymph nodes are the most common sites for infiltration, with 80 to 95% of patients demonstrating bone lesions at some time during the course of illness. LCH was previously known as histiocytosis X and grouped into three forms based on clinical manifestations. What was previously labeled eosinophilic granuloma, Hand-Schüller-Christian disease, and Letterer-Siwe disease are now referred to as localized, chronic recurring, and acute/subacute disseminated LCH, respectively. The disease process occurs during the first 3 decades of life, with a peak between 5 to 10 years. Males are more often affected, and the disease is less prominent outside the Caucasian population. Overall, the disease is rare, representing <1 to 2% of biopsied bone lesions. The disseminated form is found primarily in infants, whereas isolated bone lesions are seen in the 5- to 10-year-old age group.

Etiology

The cause of LCH is unknown. Spontaneous resolution in some cases and a response to steroids in others has suggested a possible infectious (viral) etiology. Immunologic alterations in various patients support the concept of a disorder of immune regulation. The disease is usually sporadic; however, an autosomal recessive inheritance has been proposed by some researchers.

Clinical Findings

Figure 101C Frontal skull radiograph depicts multiple, mostly ill-marginated lytic lesions.

Figure 101D