1 Introduction

Despite advancements in radiology and chemotherapy, tuberculosis continues to be a major international problem and affects approximately one-third of the world's population, every year there are about 20 million prevalent cases and 8 million new cases.¹ Skeletal tuberculosis primarily affects weight – bearing joints. Tuberculosis of pelvic girdle has been scarcely reported and is mostly restricted to the sacro-iliac joints.^2,3 Pubic osteomyelitis is an infection of the pubic bone and joint and is most frequently caused by S. aureus. It is rare condition and is seen in less than 1% cases of osteomyelitis.⁴ The exact pathogenesis is debatable but the infection most commonly arises from hematogenous dissemination and rarely from an adjacent infective focus.^5,6

2 Case report

An 8-year-old female child presented with chief complaints of pain and swelling in the Right inguinal region along with on and off episodes of evening rise of temperature since 2 months. There was no history suggestive of trauma, recent surgery or infection.

On clinical examination there was a 3 ∗ 2 swelling in the medial aspect of right groin which was tender on palpation. The right hip was in a flexed, abducted and externally rotated attitude with normal neurological evaluation.

Radiographs of the pelvis with both hips showed osteolytic destruction of the superior pubic ramus and medial acetabular wall on the right side (Fig. 1).

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Fig. 1 Red arrow shows osteolytic destruction of the superior pubis on the right side extending into the ipsilateral medial acetabular wall. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

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Local ultrasound of the swelling showed a well-defined hypoechoic collection of 6.8 ∗ 4.2 ∗7.4 cm with a volume of 110 ​cc with multiple echogenic foci in intramuscular plane in the anterior compartment of proximal thigh with no evidence of extension into hip joint.

An MRI of the pelvis showed osteolytic destruction of the medial wall of acetabulum, superior pubic rami and pubic bone on the right side with soft tissue collection extending inferiorly along the anterior muscular compartment of the upper thigh stretching the adductor muscles with a collection of 7.8 ∗ 5.4∗ 9 cm. Superiorly, the collection extended along the obturator muscles and retroperitoneal structures of the pelvis on right side. There was no intraperitoneal extension. Multiple enlarged iliac lymph nodes on the right side. Lumbar spine screening was normal (Figs. 2 and 3).

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Fig. 2 T2 weighted MRI coronal section shows huge soft tissue collection extending inferiorly along the anterior muscular compartment of the upper thigh.

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Fig. 3 T2 weighted MRI axial section shows soft tissue collection on the medial aspect of pelvis girdle with minimal hip joint effusion (red arrow). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

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3 Procedure

Nondependent USG guided aspiration was done under aseptic precautions and 50 ​cc of collection aspirated and pig tailing of another 20-cc done. Aspiration of pus was done and sent for analysis. Pus Culture sensitivity showed no growth. Gene Xpert TB detected low quantities of Mycobacterium tuberculosis with no Rifampicin resistance. Patient was managed conservatively with analgesics, skin traction for 2 weeks followed by physiotherapy along with Category –I Anti-tubercular chemotherapy for 18 months.

4 Follow-up and outcomes

The patient was routinely followed up every month with Complete blood counts, Erythrocyte sedimentation rate (ESR), C- Reactive Protein (CRP), Liver Function Tests (LFT). On routine follow up, swelling and tenderness diminished gradually over a period of 6 months. Anti-tubercular drugs were continued till 18 months. No complications were observed during the course of follow up.

After 18 months, complete healing of the abscess was observed, ESR and CRP had normalized. A repeat radiograph (Fig. 4)and MRI (Fig. 5) was done which showed osseous healing of the medial aspect of acetabulum and superior pubic ramus on the right side and complete resolution of the soft tissue collection.

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Fig. 4 Green arrow shows osseous healing of the of the superior pubis and medial wall of acetabulum. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

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Fig. 5 MRI coronal section image at the end of anti-tubercular chemotherapy shows no evidence of any soft tissue collection (Green arrow). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

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5 Discussion

India is an endemic country for tuberculosis. The number of cases of tuberculosis in higher socio-economic strata of population have also shown a rising trend due to a rise in number of immunocompromised individuals and use of immunomodulator drugs. The pelvic girdle is an uncommon site for tuberculous affection, with the sacroiliac joint being predominantly involved. Isolated involvement of the ilium and pubis is rare. The involvement of the pubis is usually due to hematogenous seeding of mycobacteria however in 40–50% of cases one may not find the site of primary infection. The patient usually presents late in the course of disease due to delay in diagnoses and the radiology being fairly normal in the early course of disease. Patients usually present with dull aching suprapubic pain which is worsened on weight bearing with mild restriction in abduction. As the disease progresses, they may develop an inguinal abscess which can be mistaken as a hernia and start having difficulty in walking. Some patients may also present as pyuria due to abscess breaking into the bladder wall. Pubic diastasis and instability⁷ may be caused due to destruction of the ligaments of the pelvic girdle by the infectious organism. This condition is frequently misdiagnosed as osteitis pubis which has similar clinical presentation. It is a self-limiting non infective inflammation of pubis commonly seen in young athletes due to repeated microtrauma.

A three phase bone scintigraphy helps in differentiating between osteitis pubis and osteomyelitis pubis, the latter showing uptake in all three phases.⁸

Although a rare possibility, but pubic osteomyelitis can also present as labial abscess and a thorough investigation should be undertaken to rule out any underlying bony infection.⁹

Osteomyelitis of pubis is most commonly bacterial in origin and is usually preceded by some sort of gynecological or urological surgery.¹⁰ X-rays may show a lytic lesion with variable reactive bone and surrounding osteopenia. In delayed presentations one may also see pubic symphysis disruption. MRI is a highly sensitive investigation and helps in the early diagnoses of the condition. FNAC and biopsy help in differentiating between osteomyelitis and osteitis pubis.⁵ Biopsy in a tuberculous osteomyelitis will reveal typical granulomas and histiocytes. Tuberculosis is a medical disease and effective chemotherapy is the keystone for achieving good clinical outcome. Surgery is recommended only in cases where there is no clinical improvement seen after 6 weeks of chemotherapy.¹¹ Surgery includes debridement of infective bone tissue with excision of sinus tracts if present. Use of bone grafts to fill the bone void and use of an implant to bridge the defect is controversial in the setting of infection with some authors recommending grafting while other authors not advocating such a procedure. It is advisable to continue AKT for 18 months to ensure no relapse or recurrence of treatment.¹² Literature has shown that effective AKT alone has provided good clinical and functional outcome in almost all cases of tuberculous osteomyelitis of pubis. The treating clinician should be aware of this condition even though it is extremely rare as early diagnosis will lead to reduced disease morbidity.

6 Conclusion

Tuberculosis of the pubis is a rare entity and one needs to keep a high degree of suspicion to diagnose the case early. With the advent of effective anti-tubercular chemotherapy complete resolution is usually achieved with a good clinical outcome. The case we have reported is a first at such a young age group.

Funding/sponsorship

This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.

Informed consent

Due informed consent has been obtained from the father of the patient.

Institutional ethics committee approval

Not applicable.

Authors contribution

First author – Data Curation, Writing - Original Draft, Writing - Review & Editing.

Corresponding author¹– Visualization, Data Curation.

Corresponding author²– Supervision, Project administration.

Corresponding author³ - Resources.

Corresponding author⁴ – Supervision.