Age / Sex : 56 / F

Chief complaint: Prolonged right thigh pain for 2months

Incidental abnormal finding on pelvic MRI

What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

(Please submit only one answer)

Courtesy: Hye Jung Choo, Inje University Busan Paik Hospital

Hyperparathyroidism

Discussion

Findings:

Simple radiography of pelvis

-       Multiples osteolytic lesions at the bilateral femors and pelvis

-       Fracture at the bilateral superior and inferior pubic rami

-       Widening of the bilateral sacroiliac joints

Pelvis MR

-       Multiple cystic lesions at the bilateral pelvic bones and femurs

-       Subcortical bony edema at the pelvis and bilateral femoral shafts

Lab

-       Elevation of serum calcium & parathyroid hormone

Thyroid US (not shown)

-       Mass at the left lobe of thyroid

-       Surgery proven – Parathyroid carcinoma

Differential Diagnosis:

Diagnosis: Brown tumors induced by hyperparathyroidism

Discussion: Brown tumors

•       Non-neoplasmic, reactive osteolytic lesion

–      Encountered in patient with primary or secondary hyperparathyroidism

–      Primary (3%) : parathyroid adenoma (m/c), parathyroid dysplasia or carcinoma

–      Secondary (1.5~1.7%) : renal osteodystrophy, chronic renal failure

•       Pathogenesis

–      Elevated level of parathyroid hormone (primarily or secondarily)

–      Skeletal calcium is mobilized to maintain normal serum calcium level

–      Increased rapid osteoclastic turnover of bone

–      Result in osteopenia, subperiosteal bone resorption

–      Reactive proliferation  of fibrovascular tissue in bone marrow by microfracture and hemorrhage, causing influx of multinucleated macrophages 

–      Frequently undergo cystic degeneration

•       Clinical symptoms

–      Depend on the size and site of bone lesion

•       Histopathologically

–      Hypervascular fibroblastic stroma

–      Foci of hemorrhage

–      Accumulation of osteoclastic multinucleated giant cells

•       Radiologic types

1)     Solid lesion as purely solid tumor without cystic portion

2)     Mixed lesion as a partially cystic tumor

3)     Cystic lesion as purely cystic tumor with multiple thin septa

•        

References:

Hong WS, Sung MS, Chun KA, et al. Emphasis on the MR imaging findings of brown tumor: a report of five cases. Skeletal Radiol 2011 Feb;40(2):205-13