Langerhans cell histiocytosis in the iliac wing

Case contributed by Dr Yair Glick

Presentation

Complains of pain attacks in right medial thigh, asymptomatic between attacks.

Patient Data

Age: 16 years
Gender: Female

No evidence of any bone lesion, periosteal reaction or soft tissue mass.
Sacroiliac and femoroacetabular joints appear normal, with no sign of excessive fluid around the latter.

Multiphase bone scintigraphy

Nuclear medicine

Multiphase bone scintigraphy - total body SPECT with Tc-99m MDP

A two-phase bone scan was performed: in the soft tissue phase, 3 minutes after injection, the pelvis and lower extremities were scanned. In the bone phase, 3 hours after injection, the entire skeleton was scanned. In addition, a SPECT of the pelvis and lumbar spine was performed.

Findings:

In the soft tissue phase, hyperemia was visible along the anterior part of the right iliac wing, above the acetabulum. An additional hyperemic focus was visible in the sacral region slightly to the right of the midline.

In the bone phase, focal pathological uptake in the right iliac bone was visible, at the anterior aspect above the acetabulum, surrounded by diffuse increased uptake. On part of the SPECT images, there is the impression that of a ring-shaped uptake. No abnormal uptake in the sacrum or other parts of the skeleton.

Summary:

  1. Pathological concentration in the right ilium above the acetabulum with adjacent soft tissue hyperemia. There is a wide differential diagnosis. It should be noted that uptake in this location with these characteristics is compatible with LCH; however, it is not specific to it. The uptake also raises the possibility of osteoid osteoma. Other proliferative etiologies cannot be ruled out, either. Radiological evaluation of this area is essential.
  2. Hyperemic focus in the sacral region without an obvious osseous finding. The quality of this finding is unclear. Anatomical correlation is warranted for this region as well.

Intramedullary mass lesion in the right iliac wing with surrounding bone marrow edema. The lesion breaks though the medial cortex. Edema in the adjacent portion of the iliacus muscle and in the gluteus minimus muscle. The lesion measures 8 x 32 mm, perilesional edema excluded. Both the lesion and the perilesional edema enhance following contrast injection.
No involvement of the acetabular roof or right sacroiliac joint identified.
No soft tissue mass emanating from the bone.
No excessive fluid in the femoroacetabular joints.

Summary: mass lesion in the right iliac wing, as described above. Ewing sarcoma cannot be ruled out; a biopsy is mandated.

Case Discussion

The patient went on to have a biopsy taken from the iliac lesion, which yielded Langerhans cell histiocytosis. BRAF mutation status unknown.

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