In our case, diffuse osteopenia with osteolysis of phalanges on both sides and osteoporotic change in vertebrae was observed but no osteolytic lesions were seen in axial skeleton, unlike in MM, which is characterized by the presence of osteolytic lesions of the axial skeleton(2,3).

Plasma cells express osteoprotegrin (OPG) which blocks the interaction between RANKL and RANK receptor on osteoclast surface leading to impaired osteoclast resorption and preservation of bone structure(2). Unfortunately, OPG levels could not be investigated in our patient.

SSc treatment includes non-steroidal anti-inflammatory drugs, corticosteroids and immunosuppressants such as methotrexate, azathioprine, mofetil mycophenolate, and cyclophosphamide. Nintedanib, an antifibrotic agent, tocilizumab, an anti-interleukin-6 receptor antibody, and rituximab, an anti-CD20 antibody were approved for interstitial lung disease related to SSc and had showed improvement in both modified Rodnan skin score(17).

Thalidomide is used for the treatment of MM, as it acts as an anti-proliferative, antiangiogenic and inhibits myeloma tumor growth (15-17).  The previously reported cases showed that systemic sclerosis symptoms were improved greatly by the treatment used for MM (when the two conditions were associated) (18).

In our case the patient showed a substantial improvement of her symptoms after 6 months of MM treatment