Case of the Month, September 2018 Page 2

MRI of the right humerus without contrast was obtained:

Finding

There is an osseous lesion within the mid to distal humeral diaphysis measuring approximately 1.3 x 1.1 cm on axial image 6-25. It measures approximately 1.9 cm in longest craniocaudal dimension. It demonstrates T2 hyperintense
signal and intermediate T1 signal relative. There is endosteal scalloping with an approximately 5 mm cortical break at the anteromedial right humerus. There is periosteal reaction and adjacent extraosseous edema. There is bone marrow edema within the humerus extending from the mid-proximal diaphysis to the distal metaphysis.

Impression

Osseous lesion in the mid-distal humeral diaphysis with endosteal scalloping, small area of cortical break, periosteal reaction and adjacent edema. There is extensive bone marrow edema within the humerus extending from the mid-proximal diaphysis to the distal metaphysis. Differential diagnosis for osseous lesions with extensive bone marrow edema includes Langerhans' cell histiocytosis, Ewing sarcoma, osteoblastoma and lymphoma. Imaging features favor Langerhans' cell histiocytosis.

Patient underwent CT-guided biopsy of the right humeral lesion:

 Pathology result:

  • Langerhans cell histiocytosis (Eosinophilic granuloma)

Patient underwent intra-lesional injection of methylprednisolone.

Fluoroscopic image obtain intraoperatively during steroid injection:

On follow-up, patient had significant improvement in symptoms.

Frontal and lateral follow up radiographs were obtained 6 weeks after steroid injection:

Impression

Slight decreased size and decreased osteolysis of the lytic lesion of the distal shaft right humerus consistent with treated eosinophilic granuloma.

Discussion

Skeletal Manifestation of Langerhans Cell Histiocytosis / Eosinophilic Granuloma (LCH/EG)

Epidemiology

  • Skeletal system is the most common site of involvement in LCH/EG.

 Clinical presentation

  • Often asymptomatic and incidentally found on imaging studies
  • When symptoms are present, patients complain of pain, swelling and tenderness
  • Systemic symptoms such as fatigue, fever and leukocytosis can be seen

 Pathology

  • Proliferation of Langerhans cells with increased number of eosinophils, neutrophils and lymphocytes
  • These cell produces and release prostaglandin which result in medullary bone resorption and producing the symptoms
Imaging Features

Radiographs

Long Bones:

  • Permeative and aggressive appearing lesion with endosteal scalloping, periosteal reaction, cortical thinning, intracortical tunneling and associate soft tissue mass. It involves diaphysis and metadiaphysis; respecting growth plates

Skull:

  • Solidary or multiple punched out lytic lesions with no sclerotic rim, beveled edge or double contour can be seen due to asymmetric involvement of the inner and outer tables of the skull (hole within the hole sign).

Mandible:

  • Irregular lucent areas mainly affecting superficial alveolar bone; loss of lamina dura results in “floating tooth” appearance.

Spine:

  • Vertebra plana – LCH/EG is the most common cause of vertebra plana in children, more commonly affecting thoracic spine

CT

  • Similar to radiographic findings; CT better demonstrates cortical erosions and soft tissue component

MR

  • T1: usually hypointense to isointense
  • T2/STIR: hyperintense
  • T1 with Contrast: often demonstrates diffuse enhancement

Nuclear Medicine

  • Variable appearance based on histology
Treatment and Prognosis
  • Excellent prognosis when disease is confined to skeleton, especially when solitary lesion.
  • Majority of solitary skeletal lesions spontaneously resolve by fibrosis within 1-2 years
  • Treatment may be considered in symptomatic patient

Treatment Options

  • Excision and curettage
  • Steroid therapy: intralesional injection
  • Chemotherapy
  • Radiofrequency ablation
  • Radiotherapy for spinal lesion

Differential Diagnosis

  • Osteomyelitis
  • Metastases
  • Round blue cell tumors
  • Primary bone tumors
  • Lymphoma
  • Leukemia

 Sources: Radiopaedia.org, Statdx.com, uptodate.com

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