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Received：October 12, 2015, Revised：December 4, 2015, Accepted：December 17, 2015

Corresponding to：Ki Won Moon, Department of Internal Medicine, Kangwon National University School of Medicine, 1 Gangwondaehak-gil, Chuncheon 24341, Korea. E-mail：kiwonmoon@kangwon.ac.kr

pISSN: 2093-940X, eISSN: 2233-4718Copyright ⓒ 2016 by The Korean College of Rheumatology. All rights reserved.This is a Free Access article, which permits unrestricted non-commerical use, distribution, and reproduction in any medium, provided the original work is properly cited.

Case ReportJournal of Rheumatic Diseases Vol. 23, No. 5, October, 2016https://doi.org/10.4078/jrd.2016.23.5.311

Tuberculous Osteomyelitis of the First Metatarsophalangeal Joint Misdiagnosed as Gouty Arthritis

Jin-Seon Jeong1, Ji-Hyun Kim1, Sung-Hyun Park1, Jae-Hoon Jeong1, Young-Joon Ryu2, Ki Won Moon1

Departments of 1Internal Medicine and 2Pathology, Kangwon National University School of Medicine, Chuncheon, Korea

A-43-year-old man visited our clinic due to pain and swelling of his left first metatarsophalangeal (MTP) joint since 6-months ago. He was diagnosed as gouty arthritis at private clinic and took hypouricemic agent, but he had progressive pain and swelling. There was swelling, erythema and tenderness and ulceration at base of the left first MTP joint. His laboratory results showed elevated C-reactive protein and normal serum uric acid level. The plain radiograph of foot showed bone destruction of left first MTP joint. MRI revealed joint space narrowing, soft tissue swelling and subchondral cyst. He underwent excisional biopsy and histology demonstrated chronic granulomatous inflammation with caseation necrosis. Tissue polymerase chain re-action for mycobacterium tuberculosis was positive. He was diagnosed as tuberculous osteomyelitis. He started on quadruple anti-tuberculous therapy and his symptom was improved. Early diagnosis and anti-tuberculosis therapy could lead to improve outcomes. (J Rheum Dis 2016;23:311-315)

Key Words. Tuberculosis, Osteomyelitis, Metatarsophalangeal joint, Foot, Gout

INTRODUCTION

Tuberculous osteomyelitis is relatively uncommon com-pared with pulmonary tuberculosis (TB). The bones and joints are affected in just 1% to 3% of all cases of TB, and the spine and the hip are most common sites involved when bone is infected. The foot accounts for only about 10% of all cases of tuberculous osteomyelitis [1]. In the present report, we describe a case of tuberculous osteo-myelitis localized to the first metatarsophalangeal (MTP) joint misdiagnosed as gouty arthritis in a 43 year old man.

CASE REPORT

We report a case of a 43-year-old man who presented with a 6-month history of progressive pain and swelling in the left first MTP joint. There was no history of trauma. He was diagnosed as gouty arthritis and had non-ster-oidal anti-inflammatory drug, colchicine and allopurinol

in private clinic. He had suffered from continuous pain and swelling over 6-months. He denied febrile and chill-ing sense, night sweating and weight loss. He had no his-tory of TB. On physical examination there was swelling, erythema and tenderness of the left first MTP joint. The 5×5 mm sized ulceration was observed at base of the left first MTP joint area with clear discharge. The movement of the first MTP joint was limited by pain. There was warmth and redness around ulceration. Other joints looked normal and lymphadenopathy was not observed. Blood pressure was 150/90 mmHg, pulse rate 60/min, respiratory rate 20/min, body temperature 36.3oC. Blood test revealed a white cell count of 9,600/mm3 (neutrophil 58%), hemoglobin 15.9 g/dL, uric acid 4.5 mg/dL and C-reactive protein 1.637 mg/dL. Liver and kidney func-tion tests were normal. Chest X-ray showed right costo-phrenic angle blunting (Figure 1A), shifting fluid was not observed on right decubitus view. Computed tomography of chest showed diffuse pleural thickening at right lower

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Figure 1. (A) Chest radiograph showed right costophrenic an-gle blunting. (B) Computed to-mography image of chest showed diffuse pleural thickening in right lower lobe.

Figure 2. (A) There was no destruction at left first meta-tarsophalangeal (MTP) joint in foot X-ray at 6-months ago. (B) There was bone destruction at left first MTP joint on day of admission. (C, D) Magnetic resonance imaging revealed jointdestruction, soft tissue swelling and subchondral erosion in left first MTP joint.

Figure 3. Three phase bone scan image showed increased perfusion over left foot in the dynamic images. In the blood flow and pool phase, there was increased flow in the left firstmetatarsophalangeal joint area. These findings are compatiblewith osteomyelitis.

lobe (Figure 1B). Urine analysis was unremarkable, and HIV antibody was negative. Sputum acid fast bacilli test

was negative. Synovial fluid aspiration was tried in the left first MTP joint, but it was dry-tap. Polarized microscopy revealed no visible crystal. The X-ray of left foot before 6-months showed normal finding (Figure 2A), but X-ray on visit showed bone destruction of the left first MTP joint (Figure 2B). The magnetic resonance imaging (MRI)

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Figure 4. Tissue from excision biopsy of the left first metatarsophalangeal joint showed chronic granulomatous inflammation with caseation necrosis. This histologic finding is compatible with tuberculosis. (H&E: A, ×40; B, ×100).

Table 1. Summary of foot and ankle tuberculosis case series

Study Country NumberTime to diagnosis

(mo)Location

Diagnostic method

Debridement (arthrodesis)

Samuel et al. [2] India 16 22 (1∼36) Ankle joint 6Tendon/bursa 5Bone 4

Biopsy 16 10 (5)

Mittal et al. [3] India 44 - Foot – Bone 37, soft tissue 7 Biopsy 7 -Gursu et al. [4] Turkey 70 26.4 (1∼180) Ankle joint 29

Foot joint 4Synovium 6Bone 35

Biopsy 70 52 (5)

Choi et al. [5] Korea 7 11 (6∼36) Ankle joint 2Foot joint 1Bone 4

Biopsy 7 4 (1)

of left foot revealed destruction of joint, soft tissue swel-ling and subchondral erosion in left first MTP joint. (Figure 2C and 2D) Three phase bone scan showed in-creased perfusion over left foot in the dynamic images. In the blood flow and pool phase, there was increased flow in the left first MTP joint area. And delayed uptake was noted over left first MTP joint (Figure 3). The findings were consistent with osteomyelitis. The patient under-went excisional biopsy. Histology of the bone core dem-onstrated chronic granulomatous inflammation with caseation necrosis compatible with TB (Figure 4A and 4B). Acid fast bacilli stain was negative. Tissue polymer-ase chain reaction (PCR) for mycobacterium TB was pos-itive and that of non-tuberculous mycobacterium was

negative. Mycobacterium culture was also negative. The patient started on quadruple anti-tuberculous therapy, isoniazid 400 mg, rifampin 600 mg, ethambutol 1,200 mg, pyrazinamide 1,500 mg. His symptom improved after 2 months of medication. He is taking isoniazid, rifampin, and ethambutol now. Further treatment is needed for more than 7 months.

DISCUSSION

Tuberculous osteomyelitis constitutes 1% to 3% of ex-trapulmonary cases and most commonly affected sites are spine, femur, tibia, and fibula [1]. The ankle and foot are rarely affected and account for only 1% of all TB

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infections. TB of foot and ankle was reported globally es-pecially in developing countries [2-4]. There have been two case series of foot and ankle TB in Korea [5,6]. One of them was about TB osteomyelitis of tarsal bone in infants. We summarized case series of foot and ankle TB of Korea and foreign countries in Table 1. In foot, the lesion in-volves calcaneum, talus, first metatarsal and navicular bones in order of decreasing frequency. Pulmonary in-volvement is uncommon and present in less than 50% of cases [7]. In our case pleural thickening was observed, we tried ultrasound guided thoracentesis twice, but it failed because of scanty pleural fluid. We did not perform pleu-ral biopsy because we could presume TB pleurisy clin-ically based on the results of bone biopsy and TB-PCR in foot lesion. The route of infection is thought to either di-rect inoculation or secondary to lymphohematogenous dissemination to the bone at the time of initial pulmonary infection, with local reactivation at a later date [8]. The clinical manifestations of tuberculous osteomyelitis in-clude joint pain, swelling and limited range of motion. Chronic discharging sinus or chronic skin ulcer might be present in longstanding cases [9]. Groin lymphadenop-athy may be present. Its diagnosis becomes more difficult in the absence of

pulmonary symptoms. Systemic symptoms such as fever, night sweat and weight loss may be present in 50% cases. Because of its indolent nature and lack of specific symp-toms, skeletal TB may underrecognized for months to years. The average duration from first symptom to diag-nosis varies depending on reports, it was between 11 to 26 months in most studies [1]. The rarity of the problem and a low index of suspicion often lead to delayed diag-nosis and potentially worse outcomes. In our case, pa-tient had no systemic symptoms like fever or night sweating. He took non-steroidal anti-inflammatory drug, colchicine and allopurinol because he was misdiagnosed as gouty arthritis. He was not diagnosed properly until 6 months after symptom on-set. Lack of awareness and a confusing clinical and radiological picture, there is often misdiagnosis such as chronic osteomyelitis, gouty arthri-tis or secondary malignancy. When tuberculous osteo-myelitis involves the first metatarsal bone as our case, it can be misdiagnosed as gouty arthritis. The difference of clinical course of two diseases can be a clue for differential diagnosis. Gouty arthritis usually showed intercritical in-flammation attack, but TB osteomyelitis manifests as chronic inflammation without intercritical period. Response to medication, radiologic and histologic find-

ings can also help differential diagnosis.The radiologic features of tuberculous osteomyelitis are

nonspecific. The plain radiography is necessary for de-tecting bone destruction, but radiographic features are noted 2 to 5 months after symptom on-set, only a joint ef-fusion is early sign in most cases [1]. MRI is accepted as most useful imaging modality in aiding diagnosis and re-vealing the extent of the disease. MRI is useful for looking at bone marrow edema, cortical erosions, joint effusions and soft tissue collections [10]. Bone scintigraphy is use-ful test for tuberculous osteomyelitis due to its high sen-sitivity up to 90%. The whole body survey can detect mul-tiple sites of involvement and be useful in assessing the treatment response of the anti-TB therapy. Radionuclide imaging using with 99mTechnetium, 111Indium, 67Gallium citrate or 18F-fluoro-2-deoxy-D-glucose positron emis-sion tomography was usually performed [11]. Our pa-tient showed bone destruction at left first MTP joint on plain radiography. MRI revealed destruction of the left first MTP joint with soft tissue swelling. Three phase bone scan image was compatible with osteomyelitis. Definitive diagnosis of tuberculous osteomyelitis is es-

tablished by histologic finding and culture results of bone tissue. Bone tissue can be obtained by computed tomog-raphy guided fine needle aspiration or surgical biopsy [12]. Histologic finding shows caseation necrosis sur-rounded by chronic inflammatory cells including epi-thelioid histiocytes and giant cells [13]. Positive acid-fast bacilli stain does not differentiate between tuberculous and non-tuberculous mycobacteria. The DNA detection via PCR is highly sensitive and specific method for diag-nosis mycobacterial TB [14,15]. Initial empirical treat-ment is same as the standard regimen for active pulmo-nary TB. Duration of treatment is 9 to 12 months. Surgery is reserved for biopsy to establish the diagnosis, debride-ment of abscess and infected tissue for failure of medical treatment. Routine surgical treatment is not warranted. Early diagnosis and medical treatment is important for re-covery and joint rehabilitation.

SUMMARY

Tuberculous osteomyelitis is rare disease. There is often a delay diagnosis because of nonspecific symptom and sign. Definite diagnosis is bone biopsy. Early diagnosis and prompt initiation of chemotherapeutic medication is important in order to avoid further destruction of the joint.

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CONFLICT OF INTEREST

No potential conflict of interest relevant to this article was reported.

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