Lesions of Unknown Histogenesis: Langerhans Cell Histiocytosis and EwingSarcoma

Abstract

Langerhans cell histiocytosis (LCH) and Ewing sarcoma represent lesions of unknown histogenesis. Both lesions typically affect children and adolescents. Imaging features frequently suggest the diagnosis, and both lesions may demonstrate aggressive characteristics. LCH shows a broader spectrum of imaging findings, depending on lesion activity and location, which are reviewed in this article. Ewing sarcoma typically reveals both osseous and soft tissue involvement, although direct continuity of the components is often not apparent. Knowledge of the spectrum of clinical and radiologic features facilitates early diagnosis and can be used to evaluate the effects of therapy.

Atypical localization of intraosseous angioleiomyoma in the rib of a pediatric patient: a case report

“…Ewing sarcoma is the second most frequent malignant bone tumour in children, with a peak incidence in the second decade of life [18, 19]. In general, the extraosseous soft tissue component of Ewing sarcoma tends to be larger compared with its intramedullary component, especially when the flat bones are involved [20]. Heterogenous appearance and hypo- to isointensity on T1W are typical characteristics of Ewing sarcoma that partially matched our case with mostly high signal intensity on T1W.…”

Primary Tumors of the Spine

“…The thoracic segments are more commonly affected than the lumbar and cervical regions. 31 Radiologically, LCH demonstrates focal lytic lesions that may progress to uniform vertebral collapse forming the classic appearance of "vertebra plana," which is seen in only $ 15% of cases. The end plates are typically preserved.…”

“…MR imaging is useful in discriminating active disease from chronic changes, which are seen as vertebral body deformity without abnormal signal intensity. LCH can be self-limiting if involvement is restricted to bone and may not require active treatment, 31 but close observation is necessary to exclude progression of disease. Therapeutic options include low-dose radiotherapy, steroid injections, chemotherapy, and surgical curettage.…”

Case 2: a 10-year-old girl with hip pain

“…Up to 95% of these lesions occur in Caucasians with less than 2% of primary osseous Ewing sarcoma occurring in African Americans [2,9]. As with many bone lesions, the primary symptoms are pain, mass and swelling, though inflammatory signs and symptoms may be present, including fever, elevated erythrocyte sedimentation rate and white blood cell count.…”

“…Osteomyelitis and trauma are common throughout childhood and should be kept in mind as possibilities for most pediatric bone lesions. Up to 95% of Ewing sarcoma cases present between 4 and 25 years of age, most frequently from 10 to 15 years [2], and most localized cases of Langerhans cell histiocytosis occur from 5 to 15 years of age [9]. Neuroblastoma metastases can give aggressive bone lesions with soft-tissue masses, but 10 years of age is beyond the typical range.…”