A 19 years old male, previously healthy, presented to the emergency department with 1 month history of progressively increasing exertional dyspnea that was associated with orthopnea, paroxysmal nocturnal dyspnea, and palpitations. These symptoms were associated with influenza-like symptoms without a fever. He also had a dry cough and unintentional weight loss of 16 kg over nine months before this presentation. Physical examination revealed dyspnea and tachycardia but normal blood pressure measurements. His cardiac examination revealed an audible third heart sound with normal jugular venous pressure and no lower limb edema. There were distended superficial veins all over the right upper part of the chest, with a decrease in breath sounds at the right lower lung area with fine crepitations.
Initial electrocardiogram confirmed sinus tachycardia and right axis deviation. His lab work revealed microcytic hypochromic anemia without any evidence of bleeding, leukocytosis of 18.9 K/muL that was mainly neutrophilic with lymphopenia, thrombocytosis 446 K/muL, isolated hyponatremia of 131 mmol/L, elevated erythrocyte sedimentation rate of 55 mm/h, C-reactive protein of 63.50 mg/L, and normal cardiac enzymes, liver profile and renal function tests. HIV test was negative.
Chest x-ray showed mild right-sided pleural effusion with prominent interstitial markings on the right lung (Fig. 1). Trans-thoracic and trans-esophageal echocardiogram were done revealing a large mass infiltrating the superior vena cava (SVC), both atria, and the mediastinum. The largest part of the mass was occupying the right atrium, and it measured 4.5 x 4.3 x 4.8 cm in its largest diameters. A reduction in the ejection fraction (EF) to 35-45%, moderate to severe global hypokinesia, pericardial thickening with small pericardial effusion were also noted. Contrast-enhanced echo using perflutren lipid microspheres showed no enhancement of the mass, suggesting a non-vascular mass. He was admitted to the intensive care unit for observation and treated as a case of heart failure with possible myopericarditis and SVC syndrome.
Chest computed tomography (CT) with contrast showed a large anterior mediastinal mass infiltrating the pericardium and myocardium in both atria and left ventricle, engulfing multiple vascular components, involving multiple lymph node groups (Fig. 2, Panel A, B), and obstructing others with thrombus formation causing multiple venous collaterals over the right chest wall (Fig. 3).
These features were suspicious of an infectious process (fungal infection like aspergillosis or TB), or non-vascular tumors like lymphoma presenting as a heart mass with SVC syndrome. Mediastinotomy and biopsy from the mass were done showing necrotizing granulomatous inflammation and giant cells (Fig. 4).
At this point all cultures, acid-fast bacilli smears, and MTB polymerase chain reaction (PCR) from tissue samples were negative for MTB as the top differential diagnosis, but the patient was started empirically on anti-tuberculosis treatment (ATT; Isoniazid 300 mg, Rifampicin 600 mg, Ethambutol 1200 mg, Pyrazinamide 1000 mg) with oral corticosteroids due to high suspicion of TB infection. Tissue culture from the biopsy later on revealed M. smegmatis group. It grew from Lowenstein-Jensen medium as a rough pigmented colony in 6 days and identified using conventional biochemical methods. The patient was discharged on ATT as the patient was clinically improving, along with warfarin and anti-heart failure medications. He continued on ATT for a total of 9 months complicated by atrial flutter that was treated using ablation. A cardiac magnetic resonance was done after three years of treatment for follow-ups instead of CT because the patient developed an allergic reaction to the contrast, it showed complete resolution of the mass (Fig. 2, Panel C, D).