Lytic lesion of the left humerus
One month later, the patient was again admitted to hospital because of persistent pain not responding to analgesics. A plain radiograph showed an aggressive expansile lytic lesion of the proximal humeral metadiaphysis (Fig. 2) and a pathological fracture. Axial CT showed a lytic lesion involving the cortex and the medulla (Fig. 3). On MRI scan, T2-weighted TSE images with fat-suppression showed increased signal intensity in the humerus and the surrounding soft-tissues (Fig. 4a). T1-weighted spin echo (Fig. 4b) and enhanced T1-weighted spin echo with fat suppression (Fig. 4c) showed that in a one-month period the lesion had changed, exhibiting intense contrast enhancement and soft tissue extension. These appearances were suggestive of an aggressive lesion. A bone scintigram showed multiple lesions at the left proximal humerus, left proximal femur, left tibia and right iliac bone. An axial CT scan of the pelvis showed multiple lytic lesions involving the cortex and the medulla (Fig. 5), with erosion of the outer cortical bone in one of them. The complete biochemical workout revealed increased serum calcium (3.46mmol/l).
The preoperative biochemical analysis showed elevated serum calcium and a subsequent PTH measurement showed 1057 (normal 10-60). A diagnosis of primary hyperparathyroidism was established and the patient underwent surgery. A 5.3g parathyroid ademona was removed. The serum calcium decreased and follow-up radiographs of all lytic lesions showed progressive healing.
The commonest lesion showing fluid-fluid levels with haemorrhage on CT and/or MRI is primary or secondary ABC (1,2). The presence of fluid-fluid levels in an osseous lesion is not pathognomonic of a specific lesion (3). The association of fluid-fluid levels and brown tumours has recently been reported (4). Although not previously reported, it is not unexpected to find fluid-fluid levels in brown tumours since these tumours often contain haemorrhage (4).
1. Hudson TM.
Fluid levels in aneurysmal bone cysts: a CT feature. AJR Am J Roentgenol 1984 May;142(5):1001-4. (PMID: 6609547)
2. Davies AM, Cassar-Pullicino VN, Grier RJ.
The incidence and significance of fluid-fluid levels on CT of osseous lesions. Br J Radiol 1992 Mar;65(771):193-8. (PMID: 1547444)
3. Tsai JC, Dalinka MK, Fallon MD, Zlatkin MB, Kressel HY.
Fluid-fluid level: a nonspecific finding in tumors of bone and soft tissue. Radiology 1990 Jun;175(3):779-82. (PMID: 2160676)
4. Davies AM, Evans N, Mangham DC, Grimer RJ.
MR imaging of brown tumour with fluid-fluid levels: a report of three cases. Eur Radiol 2001;11(8):1445-9. (PMID: 11519556)