A 50-year-old male patient presented with right shoulder pain and difficulty in abducting his right shoulder for 6 months. There was no history of fever, easy fatiguability or trauma. The patient was not a known case of any malignancies. Patient was not a known case of diabetes mellitus and tuberculosis.
Radiograph of right shoulder AP view (as seen in figure 1) showed a solitary expansile radiolucent lytic lesion in the bony glenoid of scapula with no clear zone of transition and ill-defined non sclerotic margins. There was no evidence of periosteal reactions, calcifications and internal septations within. Unenhanced CT right shoulder (figures 2b and 2c) showed an ill-defined expansile lytic lesion with non-sclerotic margins centred in bony glenoid of scapula extending into adjacent blade and infraglenoid process with thinning and destruction of the cortex. An MRI (figures 3) was obtained and it showed ill-defined expansile lesion epicentered in glenoid of right scapula appearing T1 hypointense, T2/PD hyperintense with true diffusion restriction. There was no evidence of blooming on GRE sequences. To establish the final diagnosis PET CT and bone marrow aspiration were done. PET CT showed metabolically active lesion epicentered in right scapular glenoid process extending into adjacent blade and infraglenoid process. Max SUV 5.7. There was no evidence of metabolically active lesions in the rest of the skeletal system/any other viscera. Bone marrow aspiration showed features suggestive of plasmacytoma. Protein chemistry revealed increased lambda with low kappa lambda ratio. Bone biopsy of the specimen showed the tumour tissue is highly cellular with polygonal cells and hyperchromatic eccentric nuclei.
Background
Plasma cell myeloma is localized (solitary plasmacytoma- 30%) or generalized (multiple myeloma- 70%). Plasmacytomas are solitary tumours of neoplastic monoclonal plasma cells in bone or soft tissue. It is a rare tumour that is associated with latent systemic disease in most of the affected patients. It is usually seen in patients between 40 and 80 years of age, median age is 55 years and is more common in males - 2:1 [1]
Clinical Perspective
The patient presents with pain at the site of skeletal lesion due to bone destruction by the infiltrating plasma cell tumour with restriction of range of motion of the joint. Imaging is necessary to differentiate the causes of shoulder pain like rotator cuff disorders or disorders of acromioclavicular joint and glenohumeral joint [2].
Imaging Perspective
Diagnostic criteria for plasmacytoma include a single focus, bone marrow infiltration (less than 5 per cent of nucleated cells) with absence of systemic derangement, like anaemia, renal impairment and hypercalcaemia [3]. Serum electrophoresis demonstrates a monoclonal protein in most patients, but at levels lower than that seen in myeloma. Plasmacytoma are typically seen as well-defined, “punched-out” lytic lesions with extraosseous soft-tissue masses, similar in morphology to most metastatic lesions. CT demonstrates subtle lytic lesions or small soft-tissue lesions that are not seen by radiography. MRI, CT, and PET usage in the staging and evaluation of solitary plasmacytomas may unveil multiple soft-tissue masses or additional bone lesions [4]. The final diagnosis is made by bone biopsy.
Outcome
Initial treatment involves radiotherapy, with a local control rate of nearly 90 to 95 per cent. Chemotherapy is considered if radiotherapy fails [5]. Excision of the complete tumour is done with chemotherapy and radiotherapy as an adjuvant. Local recurrence is less than 5% and dissemination is seen in 35-70% of patients. Systemic therapy, such as chemotherapy or autologous stem cell transplantation, is recommended for refractory, recurrent, and multiple plasmacytomas [6]. The disease may progress to multiple myeloma with a bad prognosis [7]. Imaging helps in treatment response and monitoring of the patient.
Take Home Message / Teaching Points
In an elderly male patient with expansile lytic lesion in the scapula after ruling out metastasis a possibility of plasmacytoma should be considered.
Solitary plasmacytoma
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Based on the provided X-ray, CT, and MRI images, the following observations are noted:
Overall, the lesion is mainly located in the right scapula, presenting as a lytic, relatively well-demarcated, and expansile lesion. Considering the patient’s persistent pain and restricted movement, there is a high possibility of malignancy.
Based on the patient’s age, symptoms, and imaging characteristics, the following differential diagnoses need to be considered:
Combining the patient’s age (50-year-old male), clinical presentation (shoulder pain and limited range of motion for more than six months, with no significant trauma or other systemic symptoms), laboratory findings (e.g., serum protein electrophoresis revealing monoclonal protein, bone marrow biopsy showing focal plasma cell proliferation), and local imaging features (lytic, expansile lesion), the most likely diagnosis is
Solitary Plasmacytoma of the Scapula.
If there is still diagnostic uncertainty or the need for further confirmation, a lesion biopsy, serum/urine immunoglobulin quantification, and more comprehensive bone marrow examination may be performed to rule out multiple myeloma.
Treatment Strategy:
1) Radiation Therapy: Local radiotherapy is the first choice for solitary plasmacytoma, yielding a high local control rate (over 90%).
2) Surgical Treatment: If the lesion is large, significantly compromises bone stability, or involves a large soft tissue mass, surgical resection or internal fixation for pathological fractures may be considered, accompanied by radiotherapy or chemotherapy.
3) Chemotherapy and Other Systemic Treatments: When the lesion cannot be completely resected, recurs, or progresses to multiple myeloma, systemic chemotherapy, targeted therapy, or autologous stem cell transplantation may be considered.
Rehabilitation and Exercise Prescription (following the FITT-VP principle):
Throughout the rehabilitation process, close monitoring of pain, swelling, and range of motion is essential. If any significant increase in pain or other symptoms occurs, a medical follow-up and adjustment of the rehabilitation plan should be carried out promptly.
This report is for reference purposes only and cannot replace an in-person consultation or professional medical advice. Patients should discuss their individual conditions with a clinical physician for further assessment and personalized treatment and rehabilitation recommendations.
Solitary plasmacytoma
