Multiple Myeloma (MM) is the most common primary cancer of bone in adults. The clinical presentation of MM is varied and depends on the sites and extent of involvement. Most importantly for chiropractors, the leading clinical symptoms of MM are related to bone neoplasm and may mimic pain of musculoskeletal origin. The following is the case of a 56 year old male chiropractic patient presenting with a 6 month history of sacroiliac joint pain previously diagnosed and managed unsuccessfully as a hematoma by multiple providers. Physical examination, imaging, and laboratory investigations confirmed a diagnosis of MM. The case report describes relevant pathophysiology, clinical presentation, imaging, and management for MM, while illustrating key issues in patient management as they relate to chiropractic practice and the recognition of pathology in the context of musculoskeletal pain.

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Introduction:

Multiple Myeloma (MM) is a primary malignancy of bone marrow characterized by clonal proliferation of plasma cells and production of monoclonal immunoglobulin. It is the most common primary bone cancer in adults [1,2] contributing to 1.3% of new cancer cases in Canada and 1.9% of cancer deaths. [3] In 2008, an estimated 6000 Canadians were living with the disease, including 2100 newly diagnosed. [3] Myeloma is slightly more prevalent in males [4-6] and blacks. [4,5,7] The median age at diagnosis is 66, with the majority diagnosed over the age of 60; [8,9] however in a review of 1027 patients diagnosed with MM, 30% were under the age of 60 and the age of diagnosis ranged from 20–92. [8] The most common symptoms reported are those related to bone neoplasm including unexplained backache that is often severe and precipitated by movement. [8,11] These symptoms may motivate a patient to seek conservative care for what is assumed to be a complaint of musculoskeletal origin. This case emphasizes key components of patient management as they relate to chiropractic practice and the recognition of pathology in the context of a patient presenting with pain of presumed musculoskeletal origin.

Discussion:

Pathophysiology

The pathophysiology of MM begins with cytogenetic changes that occur in the plasma cell lineage within the bone marrow. [10] Monoclonal expansion of myeloma plasma cells within the bone marrow interferes with the production of normal blood cells. Myeloma cells produce abnormal immunoglobulin (M protein), light chain proteins (κ and λ), and other factors, such as cytokines. Excessive M protein causes hyperviscosity of the blood, whereas excessive light chains cause end organ damage (for example renal failure). Lesions of bone are largely caused by the release of cytokines [7] that promote bone resorption via upregulation of osteoclast activity, differentiation, and maturation. [7,9] Unrestrained osteoclast activation leads to the release of mediators that stimulate further clonal proliferation of myeloma cells and subsequent tumour growth. [10] The result is a vicious cycle of bone destruction and tumour growth, leading to further bone destruction.

Clinical Manifestations/Presentation

Symptoms of MM are the result of bone marrow infiltration, the development of bone neoplasms, and the effects of the disease process on the renal system. [5,7] Proliferation of abnormal plasma cells within bone marrow results in reduced production of normal blood cells causing anemia, thrombocytopenia, and leucopenia. [7] Fatigue, weakness, and malaise are common symptoms experienced by approximately 1/3 of patients, [8] most commonly due to anemia. [7,8] Thrombocytopenia causes excessive bleeding and/or bruising, whereas leukopenia leads to frequent recurrent infections. [7,10] The leading symptoms of multiple myeloma are those related to bone neoplasm. [11] Unexplained backache or bone pain in the long bones, ribs, skull, or pelvis are common presenting complaints [7,10] and may be present in up to 58% of patients. [8] Pain is often severe and precipitated by movement. [8] Pathological fractures as a result of diffuse osteopenia or expansile tumours may be the presenting complaint in 26–34% of patients. [5,7] Vertebral compression fractures are common and can result in spinal cord or nerve root compression. [2] Peripheral neuropathies and paresthesias may also occur, the most common being carpal tunnel syndrome, [7,10] Hypercalcemia becomes prominent as bone resorption continues, and can result in numerous symptoms such as: anorexia, nausea, vomiting, polydipsia, constipation, abdominal pain, bone pain, impaired concentration and memory, lethargy, muscle weakness, and itching. [7,10,24] High levels of M protein in the blood can lead to symptoms of hyperviscosity including headache and bruising. [10] Although there are many symptoms associated with multiple myeloma, studies have shown that up to 34% of patients report an absence of symptoms prior to their diagnosis. [5]

For patients experiencing pain, correct diagnosis relies on a thorough history. MM’s variable presentation makes it difficult to provide a list of symptoms that are highly sensitive or specific to confirm or rule out the diagnosis. Typically, pain of pathological origin is suspected in the presence of red flags including age over 50, a previous history of cancer, no relief with rest, and constitutional symptoms such as unexpected weight loss, fever, and fatigue. [17,18] Individually, these indicators have high specificity but low sensitivity. [17,18] The specificity of a clinical test speaks to its ability to identify true negative test results, whereas sensitivity is related to a test’s ability to identify true positive test results. With high specificity, the chance of receiving a false positive result is low; however with a low sensitivity, there is a higher chance of receiving a false negative result. When trying to rule out a condition where there is a high cost for a missed diagnosis such as malignancy, a clnical test must have high sensitivity. Due to their low sensitivity, the absence of any one red flag cannot accurately rule out the presence of significant pathology. When combined, red flags may have higher sensitivity, emphasizing the importance of asking about all possible red flags. [17] Berenson et al. suggest that multiple myeloma should be considered as a diagnosis in a patient over the age of 50 with back pain persisting for more than one month and one or more of the following symptoms; pain worse in the supine position, pain worse at night or pain that awakens the patient from sleep, band like distribution of pain around the body, pain not responding to conservative care or rest, constitutional symptoms, or progressive neurological deficit. [10] Upon hospital presentation, the patient discussed in this case reported aggravation with lying supine and occasional waking due to night pain, symptoms fulfilling these criteria that may or may not have been present initially, emphasizing the importance of continued evaluation to ensure the recognition of latent symptoms of pathology. [23]

This patient also experienced a 6 month history of worsening pain and a growing mass. The mass was initially diagnosed as a hematoma and was unresponsive to conservative management. The presence of a growing mass is a red flag, particularly where a diagnosis of hematoma is given. The natural history of a hematoma indicates that the mass should have diminished in size, rather than increase over 4–6 weeks. Failure to respond to conservative care is another significant red flag. The Glenerin Guidelines (1996) suggest that lack of improvement after 12 visits may imply the diagnosis is incorrect, the treatment is incorrect, or there is a co-existing condition. After 6 weeks of no improvement, a referral is warranted. [19] Guidelines, however, do not take the place of clinical reasoning. Clinical decision making is guided by case complexity, the best available evidence, provider expertise and experience, and patient preference and beliefs. [20-22] A decision must be made prior to implementation of care regarding expectations for improvement based on available evidence regarding natural history and individual patient factors or case complexity. [20] A lack of expected improvement warrants a change in treatment approach or referral. [20-22] Information regarding a patient’s progress is obtained from continued frequent evaluation; even when a diagnosis has been provided by another health professional. It is the consulting health professional’s responsibility to re-evaluate and formulate a diagnosis that is consistent with history and physical examination findings as well as the patient’s response to management given previous diagnoses. For the patient in this case who was treated for pain of musculoskeletal origin and a hematoma, the natural history of the complaint should have been considered. Combined with his emerging symptoms consistent with pathology, his lack of response to conservative management should have resulted in an earlier decision for imaging or referral.

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