Multiple myeloma is a malignant plasma cell disease that occurs in B-lymphocytes. It predominantly occurs in middle-aged and elderly people, but in recent years, the incidence has increased and the age of onset has tended to advance. The misdiagnosis rate of this disease is very high. Patients may be misdiagnosed as respiratory infection, nephritis, or bone disease due to fever, urinary changes, and back and leg pain, which may delay the disease. It should be given sufficient attention in the diagnosis and treatment.
In addition to the common clinical manifestations of anemia, infection, bleeding hematologic disease, MM may have other clinical manifestations such as bone pain (fracture in severe cases), proteinuria (even uremia), hypercoagulable state or venous thrombosis.
The clinical misdiagnosis rate of MM is as high as 40-50%, and the common clinical manifestations causing misdiagnosis are as follows.
I. Infection
Multiple myeloma is prone to recurrent infections because of the reduction of normal immunoglobulins and the increase of abnormal immunoglobulins without immune activity; leukopenia, anemia and radiotherapy affect normal immune function. Patients may present with fever as the first symptom. Patients are prone to respiratory tract infections such as epiglottitis, pneumonia or urinary tract infections, and female patients are more prone to urinary tract infections. In the late stage of the disease, infection is one of the main causes of death.
Therefore, for middle-aged and elderly patients with recurrent infections, they should not be limited to anti-infection treatment only, but should be treated with anti-infection treatment while actively looking for the presence of primary diseases. If the patient has combined bone pain, anemia and bleeding, the possibility of this disease should be considered.
II. Myeloma bone disease
Bone pain and osteolytic bone destruction are the prominent clinical manifestations of this disease. The most common site of bone pain is the lower back, followed by the sternum, ribs and lower limb bones.
Since patients with this disease often have severe osteoporosis, pathological fractures often occur with slight force or inadvertently, which can cause neurological symptoms due to mechanical compression and, in severe cases, paraplegia. If the paraplegia is prolonged, even after effective treatment, it is difficult for the patient to resume walking, which greatly affects the patient’s quality of life.
Skeletal masses may also develop, with tumor cells infiltrating the bone, periosteum and adjacent tissues from the bone marrow outward to form a mass.
Isolated plasmacytomas confined to one site are less common and may eventually evolve into multiple myeloma.
X-rays are important in the diagnosis of this disease. Positive lesion sites are mainly in the skull, pelvis, ribs, vertebrae, and also in the bones of the extremities. Typical manifestations are the following three.
① Penetrating chisel-like osteolytic lesions, which are multiple round-like translucent areas, are the special X-ray manifestations of the disease. The skull and pelvis are the most easily detected.
(ii) Diffuse osteoporosis. ③Pathological fractures, most commonly in the lower thoracic and upper lumbar spine, but also in the ribs and other places. MRI is feasible in suspected cases to clarify the site of osteolytic lesions.
Patients may not pay attention to bone pain or lumbar pain, or they may visit orthopedic departments and be misdiagnosed with sprains, fractures, bone tuberculosis or bone tumors, thus delaying their condition.
Therefore, for middle-aged and elderly patients with severe osteoporosis or fractures, this disease should be considered in the diagnosis. Pay attention to check blood immunoglobulin and serum protein electrophoresis, etc. for early and clear diagnosis.
The comprehensive diagnostic value of common imaging tests for MM patients is in the following order: PET-CT>MRI (MRI) >CT>X-ray.
III. Myeloma nephropathy
Renal disease becomes a common and important lesion in this disease. The clinical manifestations are proteinuria most commonly, followed by hematuria. Late stage can develop into chronic renal insufficiency or uremia, which is one of the main causes of death in this disease.
Foreign studies have found that patients with MM nephropathy have mild pathological glomerular lesions and severe tubulointerstitial lesions, so patients rarely develop hypertension clinically.
Myeloma nephropathy is caused by a variety of factors. Damage to renal tubules by light chain proteinuria and amyloidosis caused by deposition of light chain in glomeruli are the main causes, in addition to myeloma cell infiltration, hypercalcemia and hyperuricemia are also involved in the pathogenesis.
Immunophenotyping is closely related to renal damage, with the highest rate of renal damage in the light chain type.
Patients may consult nephrology or TCM departments for hematuria or proteinuria, and be misdiagnosed as nephritis, etc. without effective treatment for a long period of time, making the disease progress to advanced stage or develop to uremia.
Therefore, for middle-aged and elderly patients with long-term proteinuria and hematuria that cannot be diagnosed clearly, renal biopsy, bone marrow aspiration or bone marrow, blood immunoglobulin and serum protein electrophoresis and other myeloma-related tests should be performed promptly.