The International Journal of Mycobacteriology

CASE REPORT
Year
: 2021  |  Volume : 10  |  Issue : 3  |  Page : 327--329

Tuberculosis presenting as metastatic lung cancer


Sarfraz A Saleemi1, Bader Alothman1, Mohammed Alamer1, Sultan Alsayari1, Abdulaziz Almogbel1, Shamayel Mohammed2,  
1 Department of Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
2 Department of Pathology, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia

Correspondence Address:
Sarfraz A Saleemi
Department of Medicine MBC 46, King Faisal Specialist, Hospital and Research Center, Riyadh 11211, PO Box 3354
Saudi Arabia

Abstract

Mycobacterium tuberculosis infection (TB) masquerading as lung tumor is well reported, but its mimicry as metastatic thoracic cancer is rare. We report the case of a young male who presented with clinical and radiological picture of lung cancer but investigations confirmed it as TB. A 35-year-old male, with 18-pack year of smoking history, presented with dry cough, anorexia, weight loss, and lower back and left hip pain. Chest imaging showed right upper lobe speculated mass with mediastinal and hilar lymphadenopathy and a lytic lesion in the left sacral area. Magnetic resonance imaging of the spine and pelvis revealed lytic lesion in the left sacrum. Fluorodeoxyglucose positron emission tomography computed tomography scan of the whole body showed hypermetabolic lung lesion with ipsilateral mediastinal, supraclavicular, splenic, and bone metastasis in the left aspect of the sacrum. Computed tomography (CT)-guided biopsy of the lung lesion showed necrotizing granuloma and tissue culture was positive for pan-susceptible M. tuberculosis. Follow-up CT scan showed complete resolution of the lung lesion and lymph nodes after anti-TB treatment with significant reduction in the sacral lesion. Mycobacterial infection may mimic metastatic lung cancer and should always be considered a differential diagnosis.



How to cite this article:
Saleemi SA, Alothman B, Alamer M, Alsayari S, Almogbel A, Mohammed S. Tuberculosis presenting as metastatic lung cancer.Int J Mycobacteriol 2021;10:327-329


How to cite this URL:
Saleemi SA, Alothman B, Alamer M, Alsayari S, Almogbel A, Mohammed S. Tuberculosis presenting as metastatic lung cancer. Int J Mycobacteriol [serial online] 2021 [cited 2022 Jan 25 ];10:327-329
Available from: https://www.ijmyco.org/text.asp?2021/10/3/327/325506


Full Text



 Introduction



Tuberculosis (TB) is still considered a major public health concern worldwide and is one of the top 10 causes of mortality.[1] In Saudi Arabia, it is estimated that the prevalence of latent TB infection is between 9.1% and 9.3%.[2] Those with latent TB infections are at risk of developing active TB and possibly become infectious. The disease mainly affects the lungs; however, extrapulmonary or disseminated forms can also happen secondary to hematogenous and lymphatic spread of Mycobacterium tuberculosis Bacilli (MTB).[3] Because of its protean clinical manifestations, the diagnosis of extrapulmonary TB is often challenging, as it is based on clinical, radiological, microbiological, and histopathological findings. Lung cancer, on the other hand, is the leading cause of cancer mortality worldwide.[4] Because of clinical and radiological resemblance, confusion in the diagnosis between TB and lung cancer is historic. Prytz and Hansen reported in 1976 a total of 91 patients who were suspected of having lung cancer, and were found to have pulmonary TB after thoracotomy.[5] TB can present as an endo-bronchial lesion,[6] but masquerading as metastatic lung cancer is rare.[7],[8]

We present an unusual case of TB, which presented like a metastatic lung cancer on diagnostic imaging. It highlights the diagnostic challenges faced by many clinicians when these two entities coexist in the differential diagnoses. Confirming the diagnosis of TB on a culture basis is the gold standard, nonetheless, time-consuming. In the instance of extrapulmonary TB, sampling the affected site for acid-fast Bacilli (AFB) stain, MTB polymerase chain reaction (PCR), mycobacterial culture, and histopathologic evaluation is recommended. However, false-negative AFB stain and MTB PCR are relatively common and cannot be used to exclude TB.[9] Therefore, initiation of empiric anti-TB therapy is sometime warranted, based on clinical factors, and index of suspicion, with close monitoring of symptoms, and radiological resolution, pending culture results.[10] However, empiric anti-TB treatment in a suspected lung tumor may delay the diagnosis of lung cancer where early confirmation of diagnosis is crucial for better outcome.[11]

 Case Report



A 35-year-old male with a history of 18-pack year of smoking and no significant medical background presented with lower back and left hip pain. He also reported mild cough, anorexia, and weight loss of about 10 kg over a 2-month period preceding presentation. His physical examination was unremarkable except lower back tenderness without restriction of movements. Routine laboratory tests including complete blood count and biochemical profile were within the normal range. Chest X-ray showed right apical lesion and levoscoliosis. An Magnetic resonance imaging (MRI) of the lower spine and pelvis demonstrated an enhancing lytic lesion in the left aspect of the sacrum. CT scan of the chest showed right upper lobe mass with speculated edges measuring 2.3 cm × 5 cm × 2.7 cm associated with satellite nodules and pleural tethering along with right prevascular, right para-tracheal, sub-carinal, and right hilar hypodense lymphadenopathy. Upper abdominal section showed multiple hypo-dense splenic lesions and two necrotic lymph nodes in the peri-splenic area [Figure 1]. A whole-body fluorodeoxyglucose positron emission tomography (FDG-PET) scan demonstrated hyper-metabolic right upper lobe lesion with standard uptake value (SUV) of 8.5, indicating neoplastic process with mediastinal, right supraclavicular, splenic, and sacral bone metastasis [Figure 2].{Figure 1}{Figure 2}

A computed tomography (CT)-guided needle core biopsy of the right upper lobe lesion showed necrotizing granuloma and no evidence of malignant cells [Figure 3]. A purified protein derivative skin test was reactive. With a presumptive diagnosis of MTB infection, the patient was started on anti-TB treatment. Tissue culture later-on was positive for pan-susceptible M. tuberculosis. A follow-up CT scan of the chest, after 4 months, showed almost complete resolution of lung mass, lymph nodes, and splenic lesions with minimal residual scarring in the right upper lobe [Figure 4]. Repeat MRI of spine demonstrated interval decrease in the size of sacral lesion [Figure 5]. His symptoms of cough, anorexia, and lower back pain improved, and he had documented weight gain.{Figure 3}{Figure 4}{Figure 5}

 Discussion



M. tuberculosis (MTB) is known to affect multiple organs. Pulmonary TB may mimic lung cancer, although presentation as metastatic lung neoplasm is rare. A speculated lung mass with mediastinal lymph nodes and distant lesions is an unusual feature of MTB and in the presence of smoking history, it raises the suspicion of metastatic lung cancer. FDG-PET scan may not differentiate between malignant lesion and active TB infection and high SUV in both conditions further complicates the diagnosis.[12] This case highlights the diagnostic dilemma when clinical and radiology features are highly suggestive of lung cancer in view of smoking history, lung lesion with speculated margins, and distant lesions suggestive of metastasis along with high SUV on FDG-PET scan. TB should always be considered a differential diagnosis of a lung lesion, especially in TB-endemic areas. There are reports of coexistence of lung cancer and TB as patients with lung cancer has increased vulnerability to MTB infection and pulmonary TB may reactivate during the treatment of cancer.[13],[14],[15]

 Conclusion



TB is known to have various clinical manifestations, and this can pose certain challenges in diagnosis, leading to increased morbidity and mortality. In our patient, TB disguised as a metastatic lung cancer. This case illustrates that in TB endemic areas such as Saudi Arabia, TB should always be thought of, and excluded, in patients presenting with a clinical picture of metastatic disease.

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.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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