Teaching Case

A 40-year-old female patient presented with diplopia and headache.
Laboratory investigations revealed
Hb : 9 g/dL
S. Calcium level: 15 mg/dL (borderline high).

MRI brain:
Altered signal intensity lesion involving the anterior aspect of clivus extending to the bilateral parasellar region involving the both cavernous sinuses.
It appears isointense on T1W and hypointense on T2W.
Post-contrast study revealed homogeneous enhancement of the lesion.
Similar characteristic enhancing soft tissue lesions were seen involving the rami of the mandible on either side.
PET scan:
Multiple hypermetabolic lesions involving the axial and appendicular skeleton (MAX SUV: 18).
CT scan guided tru-cut biopsy:
From left para-vertebral soft tissue at dorsal vertebra.
Sent for histopathology examinations.

Multiple myeloma is most common primary osseous malignancy of the older age group. The most common affected age group is 40 -80 years [1].
It is a disorder of plasma B cells associated with bone marrow infiltration and overproduction of monoclonal immunoglobulins.

The common presentation of the disease is generalised weakness, bone pain, pathological fracture or signs of neural compression.

The primary blood investigations include complete blood count, which demonstrates anaemia.
The further investigations are done with electrophoresis, which demonstrates increase in monoclonal immunoglobulin (M protein).

Radiological investigations are suggested for staging and prognosis.

Classical findings on X-ray show generalised osteoporosis with multiple well-defined punched-out lytic lesions without rim of sclerosis in the axial and appendicular skeleton. However, in 10-20 % skeletal survey does not reveal abnormal findings [2] and it is difficult to differentiate from the osteoporosis of the other cause like age-related, steroid-induced or alcohol intake-related. So in modern era the use of cross-sectional imaging with CT scan, MRI and PET-CT is increasing for the staging purpose or to evaluate any complication.

CT findings in multiple myeloma included osteoporosis with lytic lesions with or without the soft tissue component. CT is superior for detecting the risk of fracture. It is also useful in guiding the biopsy. However, due to high degree of radiation exposure its role is limited.

MRI is the useful modality for the early diagnosis of marrow changes in absence of identifiable lytic lesions on X-ray or CT scan. Nowadays it emerged as most sensitive modality for detection of focal or diffuse involvement in the spine as well as the extra-axial skeleton [3, 4]. Typical multiple myeloma lesions appear hypointense on T1W and hypertensive on T2W images. Post-contrast study shows homogeneous enhancement of the osseous lesions as well as extra-osseous soft tissue. However, sometimes lesions appear hypointense on T2W images depending upon the plasma cell percentage (between 10-50%) [5]. Major advantage for the MRI is no radiation exposure, so it can be used for the follow-up imaging.

On FDG-PET multiple myeloma shows high metabolic activity. It is an important tool for staging and prognosis of multiple myeloma due to its ability to pick up metabolic activity, extra-medullary disease and secondary lesions that are not attributable to multiple myeloma [6]

Take home message: In multiple lytic lesions in the axial and appendicular skeleton with involvement of the mandible, multiple myeloma should be first in the differential consideration.