Metastatic cancer masquerading as miliary tuberculosis in an immunocompetent young adult

Abstract

A healthy, immunocompetent South Asian man in his mid-20s, with a medical history of gastric ulcer, presented to Accident & Emergency with pleuritic chest pain, shortness of breath, fever, night sweats, weight loss, dry cough and asymptomatic iron deficiency anaemia. Following his initial assessment and investigations (chest X-ray, CT and blood tests), a diagnosis of miliary tuberculosis (TB) was made and empirical antimicrobial treatment started. However, subsequent microbiological testing, including urine, blood, induced sputum and lymph node sampling, was negative. Being interpreted as non-diagnostic, the antimicrobial therapy was continued. Following a clinical deterioration while on treatment, the patient's case was re-evaluated and further investigations, including a repeat CT and a liver biopsy, confirmed a diagnosis of stage IV (T1aN3bM1) gastric carcinoma. Our case highlights the diagnostic challenges in differentiating metastatic cancer from miliary TB. We also focus on possible cognitive biases that may have influenced the initial management decisions.

Keywords: Gastric cancer; Respiratory system; TB and other respiratory infections.

Figure 1

Chest X-ray on admission. It showed reticulonodular shadowing throughout both lung fields, bilateral blunting of costophrenic margins and a small left-sided pleural effusion.

Figure 2

CT scan of the thorax. This transverse slide illustrated the interlobular septal thickening and bilateral effusion.

Figure 3

Chest X-ray on second admission. It identified worsening right effusion, widespread nodular shadowing and bilateral hilar lymphadenopathy.

Figure 4

Cumulative diagnostic yield of various body fluids and specimens in the diagnosis of miliary tuberculosis. While the yield cannot be comparable across series due to the lack of standards in criteria employed across studies, it can be used appropriately in an individual patient to establish the diagnosis of miliary TB. Adapted from Sharma et al. BM Asp, bone marrow aspirate; Bx, biopsy; CSF, cerebrospinal fluid; FOB, fibreoptic bronchoscopy; LN, lymph node.

Figure 5

A line graph comparing the tuberculosis incidence rate per 100 000 people in the Czech Republic and the UK between 2000 and 2018. It showed a consistently lower incidence in the former since 2004. Its incidence is also 48% lower than that of the UK in 2018 comparatively (5.4 vs 8.0 per 100 000 people). Adapted from the Global Tuberculosis Report, by the WHO.