|Year : 2018 | Volume
| Issue : 1 | Page : 126-129
Multifocal skeletal tuberculosis mimicking multiple myeloma and secondary bone metastasis: An unusual case scenario
Gurjeet Singh Chowdhary1, Abhishek Purkayastha2, Ritu Mehta3
1 Department of Medical Oncology, INHS Asvini, Mumbai, India
2 Department of Radiation Oncology, Command Hospital (Southern Command), Pune, Maharashtra, India
3 Department of Onco-Pathology, INHS Asvini, Mumbai, India
|Date of Web Publication||11-Jun-2018|
Dr. Abhishek Purkayastha
Department of Radiation Oncology, Command Hospital (Southern Command), Pune - 411 040, Maharashtra
Source of Support: None, Conflict of Interest: None
Skeletal tuberculosis (TB) is rare, accounting for 1%–2% of all cases of TB with multifocal involvement being rarer. Bones most commonly involved are the spine, joints, shoulder girdle, sternum, pelvis, ribs, skull, and orbit. We hereby report such multifocal bone TB in a 58-year-old-male who presented with complaints of pelvic pain of 2 months' duration. Radiograph of pelvis showed lytic lesions left ilium. A differential diagnosis of multiple myeloma and secondary bone metastasis was initially thought of. Computed tomography scan, magnetic resonance imaging, and bone scan pointed toward metastatic bone involvement. Metastatic workup with positron emission tomography scan and myeloma workup were negative. Biopsy from the lytic bony lesion was done which revealed TB with Ziehl–Neelsen staining positive for acid-fast bacilli. He was diagnosed as a case of primary bone TB and was commenced on antitubercular therapy to which he responded significantly. This case is being reported to highlight its extreme rarity, the diagnostic and therapeutic challenges it presented, and the overall prognosis of this condition.
Keywords: Multifocal, multiple myeloma, secondary metastasis, skeletal tuberculosis
|How to cite this article:|
Chowdhary GS, Purkayastha A, Mehta R. Multifocal skeletal tuberculosis mimicking multiple myeloma and secondary bone metastasis: An unusual case scenario. Arch Med Health Sci 2018;6:126-9
|How to cite this URL:|
Chowdhary GS, Purkayastha A, Mehta R. Multifocal skeletal tuberculosis mimicking multiple myeloma and secondary bone metastasis: An unusual case scenario. Arch Med Health Sci [serial online] 2018 [cited 2019 May 25];6:126-9. Available from: http://www.amhsjournal.org/text.asp?2018/6/1/126/234089
| Introduction|| |
Extrapulmonary primary skeletal tuberculosis (TB) represents 1%–2% of all TB cases  and often presents with an indolent clinical course, leading to a delayed diagnosis with bone and joint destruction. It presents a diagnostic and therapeutic challenge to treating physicians as it mimics multiple myeloma (MM), osteoarthritis, osteomyelitis, secondary bone metastasis, or even hyperparathyroidism. Delayed diagnosis may result in the disease spreading to adjacent bone structures, leading to difficulty in proper management. Once diagnosed, the mainstay of treatment remains antitubercular drugs. Surgical resection is sometimes indicated in case of mass effect and neurological deficits in case of spinal TB.
| Case Report|| |
A 58-year-old male with no known comorbidities, chronic smoker presented with complaints of diffuse pelvic pain more on the left hip region of 2 months' duration which worsened on activity. There was a history of decreased appetite, weight loss, and fatigue. However, there was no history of trauma, night sweats, cough, fever, or loss of bladder and bowel control. He had no past history of TB or any other major medical illness. Clinically, there was tenderness over the left ilium. His complete blood count, erythrocyte sedimentation rate, and serum biochemistry including serum calcium were normal. Human immunodeficiency virus status and Mantoux test were nonreactive. Chest roentgenogram was normal. Radiograph of the pelvis showed lytic lesion left ilium [Figure 1]. A skeletal survey was done which showed no other bony lesions. Computed tomography (CT) scan pelvis [Figure 2] showed lytic lesions involving left ilium, left ala of sacrum, and right ischial tuberosity suggestive of neoplastic etiology likely MM or metastasis. Magnetic resonance imaging (MRI) scan also revealed similar findings. Bone scan [Figure 3] was performed which showed abnormal tracer concentration in the left ilium, left ischium, right ilium, left sacral ala, calvarium right parietal bone, left maxilla, manubrium, and multiple vertebrae with arthritic involvement of multiple joints of the body.
|Figure 1: Radiograph of pelvis showing lytic lesion left ilium (yellow arrow)|
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|Figure 2: Computed tomography scan pelvis showing lytic lesions involving left ilium (yellow arrow)|
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|Figure 3: Bone scan showing abnormal tracer concentration in left ilium, left ischium, right ilium, left sacral ala, calvarium right parietal bone, left maxilla, manubrium and multiple vertebrae|
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Multiple bone involvement raised the suspicion of MM. Bone marrow aspirate and biopsy showed normal trilineage differentiation with no evidence of granulomas. A battery of MM investigations including lactate dehydrogenase, beta-2 microglobulin, serum free light chain assay, serum quantitative immunoglobulins, serum protein electrophoresis, serum immunofixation electrophoresis, urine protein electrophoresis, urine immunofixation electrophoresis, and 24-h urine for total protein was negative. Whole body positron emission tomography (WB-PET) scan was done to rule out any secondary bony metastasis which was also negative. Faced with this dilemma of deciphering the exact diagnosis before starting any neoplastic treatment, a biopsy from the left ilium bone lesion [Figure 4] was done which revealed tuberculous granulomatous lytic lesion comprising of lymphocytes, plasma cells, and epithelioid cells with Ziehl–Neelsen staining positive for acid-fast bacilli (AFB) [Figure 5] with no evidence of atypia or malignant cells. Sputum sample for AFB was negative. He was finally diagnosed as primary skeletal TB and was started on anti-TB therapy using isoniazid, rifampin, ethambutol, and pyrazinamide. At present, he is clinically stable and has shown significant response to therapy with reduction in bony pain.
|Figure 4: Biopsy from the left ilium bone lesion showing tuberculous granulomatous lytic lesion comprising of lymphocytes, plasma cells, and epithelioid cells (H and E, ×100)|
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| Discussion|| |
TB is clinically divided into pulmonary TB, extrapulmonary TB, and generalized or miliary TB. Extrapulmonary TB accounts for 15%–20% of all cases of TB. The prevalence of extrapulmonary TB in immunocompromised patients is higher than 50% compared to immunocompetent patients. Constitutional and nonspecific signs and symptoms such as fever, weight loss, anorexia, malaise, and myalgia often precede the specific symptoms depending on the organ involved. The most common systems involved are the lymph nodes, osteoarticular system, central nervous system, genitourinary system, and gastrointestinal system. Least common tubercular affections are of pleura, pericardium, peritoneum, adrenal glands, and eyes. Peculiar feature in our case was multifocal involvement of different bones by TB without involving the joints which showed age-related arthritic changes. Furthermore, multifocal bone TB in an immunocompetent patient is unusual.
The multifocal skeletal involvement by TB is usually seen associated with pulmonary form; however, no pulmonary focus was present in our case. Approximately 50% cases with skeletal TB will have negative findings on chest roentgenogram. An immunocompromised host also predisposes to multifocal bone TB which is exceedingly rare in immunocompetent patients as was seen in our case. Bone TB has been reported in patients who had primary childhood TB as the disease spreads to the developing epiphysis and vertebral bodies. Bone TB generally begins in the cancellous part and produces either a more common perforating type or a progressive infiltrating type lesion. It is often difficult to promptly diagnose extrapulmonary TB, and diagnostic delay due to nonspecific symptoms can have an impact on disease progression with spread of TB to other organs or impairment of organs already affected.
Early diagnosis of extrapulmonary TB is of utmost importance to prevent structural damage. Patients with multifocal skeletal TB generally present with vague symptoms such as generalized body pain and arthralgia and may mimic benign condition like arthritis in older people or malignant condition like MM or secondary bone metastasis both clinically and radiologically. Baseline radiographs and skeletal survey are performed as the initial screening test, while CT or MRI is critical in detecting the disease which demonstrates lytic bony lesions. Although multifocal involvement raised the suspicion of MM, barely 10% cases of myeloma have increased uptake on a bone scan as the process is predominantly osteolytic rather than osteoblastic. WB-PET scan helps in detecting a primary lesion in case of metastasis to bone and detecting an active MM. Persistent FDG positivity before and after primary therapy and subsequent high-dose therapy is a predictor of prognosis. Biopsy from the affected bone remains the gold standard of diagnosis if all other investigations are negative. In our patient, based on his initial clinical findings, CT, MRI, and bone scan, we considered MM or multiple secondary metastases. Bone marrow biopsy, serum and urine electrophoresis, and urine for Bence Jones proteins were negative. Biopsy from left ilium confirmed TB.
Primary skeletal TB is a rare condition with a dismal prognosis if not treated properly and promptly. By reporting this rare occurrence, we recommend that the diagnosis of extrapulmonary primary skeletal TB mimicking a benign or neoplastic etiology should always be considered in patients presenting with symptoms of bony pain and nonspecific somatic symptoms so as to initiate an appropriate treatment strategy. Preferable therapy has been a combination of four anti-TB drugs given over for 6 months. Extended treatment up to 1–1½ years and sometimes as long as 4 years has been described  since these drugs are not known to penetrate bone or fibrous tissue deeply. Role of surgical intervention is sought in case of spinal TB causing mass effect and neurodeficit. However, a better understanding and interpretation of the biological mechanism of the disease process may help to device therapeutic strategies to counter this entity.
We thank the patient for allowing us to publish the case report and use the images taken during his stay in the hospital.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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