Differential Diagnosis
The patient's presentation suggests a hematologic disorder with bone involvement. Here's a categorized differential diagnosis:
Single most likely diagnosis
- A. Multiple myeloma: This is the most probable diagnosis given the combination of elevated protein, M-protein spike on serum protein electrophoresis, multiple lytic lesions on bone radiographs, and decreased platelets. These findings are characteristic of multiple myeloma, a plasma cell dyscrasia that can cause bone destruction, anemia, and renal impairment.
Other Likely diagnoses
- C. Monoclonal gammopathy of undetermined significance (MGUS): MGUS is a precursor condition to multiple myeloma, characterized by the presence of an M-protein spike without end-organ damage. Although the patient has bone lesions, which suggests a more advanced disease, some cases of MGUS can have limited bone involvement.
- B. Temporal arteritis: This condition, also known as giant cell arteritis, can cause elevated erythrocyte sedimentation rate (ESR) and anemia. However, it typically presents with headache, jaw claudication, and visual symptoms, which are not mentioned in the scenario.
Do Not Miss diagnoses
- D. Metastatic breast cancer: Although less likely, metastatic breast cancer can cause multiple lytic bone lesions and elevated protein levels due to paraproteinemia. It's essential to consider this diagnosis, especially in a postmenopausal woman, as breast cancer can have a prolonged latency period.
- Waldenström's macroglobulinemia: This rare lymphoproliferative disorder can cause an M-protein spike, anemia, and bone lesions. Although not listed among the options, it's a critical diagnosis to consider in the differential.
Rare diagnoses
- POEMS syndrome: This rare paraneoplastic syndrome is characterized by polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes. It can cause bone lesions and an M-protein spike, but its presentation is typically more complex and multifaceted.
- Amyloid light-chain (AL) amyloidosis: This condition can cause an M-protein spike and organ dysfunction due to amyloid deposition. Although it's a rare diagnosis, it's essential to consider in patients with unexplained organ dysfunction and an M-protein spike.