Plasma cell myeloma usually presents with multiple lytic bone lesions involving the axial skeleton. Vertebral column is one of the most commonly affected sites. The lesions range in size from 1 to 4 cm and are filled with soft, gelatinous, red-brown tumor as seen in this photograph. The most frequent presenting symptom is bone pain in the back or lower extremities due to spinal lesions. In some cases, collapse of multiple vertebra can cause loss of height or spinal cord compression. Excessive bone resorption can cause hypercalcemia which may manifest as neurologic symptoms such as confusion, weakness, lethargy, constipation, and polyuria. Image copyright: pathorama.ch.