Solitary plasmacytoma of the bone

Case contributed by Hazem M Almasarei
Diagnosis certain


Chronic left hip pain.

Patient Data

Age: 60 years
Gender: Female

There is an expansile lytic bubbly and septated lesion involving the left acetabulum and left ischium, which is characterized by:

  • no abnormal soft tissue component
  • no periosteal reaction
  • no evidence of cortical break
  • narrow zone of transition

There is an associated with left protrusio acetabulum and shortening of the left lower limb. The left head of the femur seems to be not involved. The differential diagnosis of such findings:

Benign entities as giant cell tumor, brown tumor (hyperparathyroidism) and fibrous dysplasia.

Malignant entities as plasmacytoma and metastasis.

There is a large expansile lytic lesion involving the left acetabulum, supra- acetabular iliac bone, extending into the ischial tuberosity and inferior ramus of the pubic bone. The cortex of the involved bone appears thin with areas of breakthrough. There is inward migration of the femoral head inside the pelvis. There is remodeling of the femoral head due to extrinsic pressure caused by the anterior column of the acetabulum.

Nuclear medicine

Hypermetabolic destructive bone involving the left iliac bone demonstrating heterogeneous abnormal increased FDG uptake with SUV Max of 11. No definite evidence of other medullary or extramedullary abnormal hypermetabolic lesion.

Case Discussion


Left acetabular bone, Tru-cut biopsy: Plasmacytoma.

Note: The tumor cells are positive for CD138 and show lambda light chain restriction. Kappa light chain is negative by immune-histochemistry. CD56 shows weak focal positivity.

The free light chain pattern is compatible with polyclonal pictures, while serum protein electrophoresis showed the presence of 1.5 g/dL. M protein level is less than 3 g/dL. 

By the giving above data; features are representing stage I multiple myeloma.  Solitary plasmacytoma of the bone.

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