Extraosseous multiple myeloma

Case contributed by Dr Ngo Tuan Minh
Diagnosis certain


History of multiple myeloma 3 years ago. Presented with a slowly enlarging mass in the right infraclavicular area several months ago.

Patient Data

Age: 60 years
Gender: Female

CT shows a well-circumscribed homogeneous enhancing subcutaneous mass in the right infraclavicular area. Multiple osteolytic lesions in the ribs, thoracic vertebrae, and sternum. Diffuse osteopenia is seen as well. 


The clinical photograph of the right shoulder area shows a large subcutaneous pectoral lump that has been slowly enlarging for several months.


Photomicrograph shows diffuse plasma cells with high N/C ratio, eccentric nuclei, and eosinophil cytoplasm. Tumor cells involving skeletal muscle.

Case Discussion

This case illustrates typical features of extraosseous multiple myeloma. This patient was diagnosed with multiple myeloma 3 years ago, presented with a slowly enlarging lump in the right pectoral area several months ago. Histopathology has confirmed the diagnosis. 

Extraosseous multiple myeloma is an uncommon form of multiple myeloma which found in less than 5% of myeloma patients. It can be also encountered in various part of the body such as the gastrointestinal tract, lymph nodes, spleen, parotid gland, vagina, breast, pancreas, thyroid, and testes.

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