Pulmonary tuberculous pseudotumor in a pediatric patient--A diagnostic dilemma.

Pulmonary tuberculosis (TB) can rarely resemble a large malignant tumor in immunocompetent children on imaging.[1]

A 19-months-old male child belonging to low socio-economic status was referred from a peripheral hospital to our pediatric outpatient department with complaints of intermittent low-grade fever, wet cough, and inadequate weight gain for about three months. Chest radiograph revealed a large radio-opacity in the upper and mid zones of the right lung. The child's grandfather was suffering from tuberculosis.

On examination, the patient was afebrile with mild facial puffiness. BCG scar was present. The respiratory rate was mildly increased (40 breaths/min), pulse rate, and blood pressure were normal. He had mild pallor and no icterus, clubbing, or lymphadenopathy. On auscultation, there was decreased breath sound on the right side. The abdominal, cardiovascular, and neurological examinations were within normal limits.

The Mantoux test, gastric lavage for acid-fast bacillus (AFB), and nucleic acid amplification test were negative. Blood examination showed leukocytosis. The differential blood count revealed neutrophilia and lymphocytosis. The serum test for human immunodeficiency virus (HIV) was negative. Bone marrow examination was normal. The contrast-enhanced computed tomography (CECT) scan of the thorax showed a large heterogeneously enhancing mass lesion of size 10.2 × 8.6 × 8.0 cm in the right upper and middle lobes [Figure 1a–c] with adjacent consolidation and mild pleural effusion [Figure 1c]. There were peripherally enhancing mediastinal nodes with central hypodensity [Figure 1b and c], and some of them showed peripheral calcification [Figure 1a]. The mass caused the narrowing of the right main bronchus, compression of the superior vena cava, and encasement of the right pulmonary artery [Figure 1b]. Due to easy access to the large mass, an ultrasound (USG)-guided percutaneous biopsy was planned instead of bronchoscopy.

Figure 1

(a) Axial section of the plain CT scan of the thorax showing right lung mass and mediastinal nodes with peripheral calcification. (b) Axial section of the CECT scan of the thorax showing large heterogeneously enhancing right lobe mass causing bronchial narrowing, encasement of the right pulmonary artery, compression of the superior vena cava and peripherally enhancing subcarinal lymph node with central hypodensity. (c) Coronal CECT image showing right lobe mass with adjacent consolidation, minimal right pleural effusion, and subcarinal lymph nodes

Histopathology revealed numerous well-delineated epithelioid cell granulomas and Langhans giant cells [Figure 2a]. There were large areas of caseous necrosis [Figure 2b]. Stain for AFB was positive [Figure 2c]. Antitubercular chemotherapy (ATT) was started and continued for 10 months. Follow-up after 3 months showed symptomatic and clinical improvement along with a resolution of the lung lesion on X-ray.

Figure 2

(a) Histopathologic study of the percutaneous biopsy sample from the large lung mass showing multiple well-formed epithelioid cell granulomas with Langhans giant cells. (b) Histopathologic study of the percutaneous biopsy sample from the large lung mass showing large areas of caseous necrosis. (c) Histopathologic study of the percutaneous biopsy sample from the large lung mass positive staining for acid-fast bacilli

Conglomerated lymph nodes in primary tuberculosis form the lymph nodal pseudotumor. In progressive primary or reactivation tuberculosis, there is the formation of a granulomatous parenchymal mass. The parenchymal mass formation occurs due to an unusual immunological response to the mycobacterial antigen in response to the endobronchial discharge of the contents of a cavity. In the absence of endobronchial decompression, parenchymal mass is formed by enlarging necrotic areas predominantly in the progressive primary disease.[2]

The parenchymal pseudotumoral form of TB is very rare in both children and adults and has a striking clinical, bronchoscopic, and radiological resemblance with malignant tumors.[134] It may be mistaken for intrathoracic sarcoma or pleuropulmonary blastoma.[5]

There is an approximate delay of about 4 to 10 weeks in the diagnosis of pseudotumoral TB. The clinical symptoms may be nonspecific. On bronchoscopy, it may present as an endobronchial mass or ulceration.[4] A chest X-ray shows large radio-opaque lesion predominantly in the upper and mid zones as these are the well-ventilated areas having a high predilection for tubercular infection. CT scan demonstrates a parenchymal or mediastinal mass. Lymph nodes exhibiting peripheral enhancement with central hypodensity due to necrosis are suggestive of tubercular etiology but not pathognomonic of it.[6] Calcified nodes can also occur in tuberculosis.

For accurate microbiological diagnosis, methods like sputum AFB and bronchoalveolar lavage (BAL) fluid AFB are done initially, but these may yield negative results in cases of paucibacillary TB. In that case, bronchoscopic biopsy and fine-needle aspiration cytology (FNAC), USG or CT-guided FNAC or biopsy, or surgical biopsy is done.[2]

Scanty data is available regarding the treatment of pseudotumoral tuberculosis. Patients usually show complete resolution with short-course ATT.[2] The duration of therapy may be prolonged in cases of paucibacillary and extrapulmonary disease as per clinical indication.

A timely and accurate diagnosis of tuberculous pseudotumor is necessary to prevent delay in the treatment, extrapulmonary involvement, and unnecessary surgical intervention.

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Conflicts of interest

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