Presentation of multiple myeloma occurring in the humerus after strain: a case report.

Multiple myeloma (MM) is a malignant tumor originating from plasma cells that synthesize immunoglobulin in an abnormal amount and invade the bone marrow. The presenting symptoms have usually been severe bone pain, osteolytic bone damage and pathologic fractures, hypercalcemia, kidney damage, compromised immune function, and anemia. The patient age is typically over 40, with the majority of the cases diagnosed between ages 50 and 70. MM occurs in hematopoietic locations with red marrows; most common locations include the vertebrae, ribs, skull, pelvis, and proximal long bones. It often has extensive bone destruction with no reactive bone formation and a large soft tissue component similar to the lesion. In the literature, the presence of pathological fracture in the humerus is generally seen as the first clinical manifestation of MM. In this report, it is presented a case with MM occurring in the right humerus after strain and presenting only shoulder pain without pathologic fracture.