Pulmonary tuberculosis is an endemic lung infection in our context. It is characterized by clinical and radiological polymorphism. Imaging, especially the chest computed tomography (CT) scans, plays an important role in the detection of parenchymal lesions, however, the radiological and semiological aspects of tuberculosis are multiple and non-specific. When the clinical context is evocative with multiple and evocative lung lesions, imaging can guide the diagnosis. Rarely, lung tuberculosis presents with a solitary nodule or mass making diagnosis difficult [1], [2].

A 47-year-old-female patient, having a history of pulmonary tuberculosis treated 12 years ago, was presented to the emergency department for mild dyspnea evolving for one month associated to weight loss estimated at 3 kg with productive cough.

The clinical examination found a fever at 38.2°C. The cardiovascular and respiratory examination was without particularity. Biological data showed inflammatory syndrome (C-reactive protein = 75 mg/L; erythrocyte sedimentation rate = 60 mm/h). The blood cell count was normal. Conventional chest radiography was realized showing a nodule at the right upper lobe.

Chest CT scans showed a nodule at the right upper lobe with regular margins and a central cavity measuring 10 mm in diameter, without other associated lesion of pleural effusion (Figure 1).

A bronchoscopy with bronchoalveolar lavage and biopsies was negative. A biopsy of the lesion was realized (Figure 2) using a needle of Menghini 18 Gauge and histological analysis showed necrotic changes surrounded by a thin epithelioid crown in favor of a tubercular origin. The patient was given antituberculosis drugs for six months. The evolution was marked by the regression of clinical symptoms and radiological image during a control carried out six months later.

Pulmonary tuberculosis is an endemic infectious disease caused by mycobacterium tuberculosis or Koch bacillus. The symptomatology of tuberculosis is non-specific, giving varied presentations. The general signs are dominated by weight loss and night sweats. Respiratory signs include chronic cough that may be dry or productive, associated to purulent or hemoptoic sputum. Chest pain is infrequent [2]. The diagnosis is confirmed by the identification of BK in pathological specimens. Bronchoscopy is useful to detect endobronchial involvement with possibilities of bacteriological and histological samples, as well as therapeutic gestures [3], [4].

When the diagnosis cannot be made by bacteriology techniques, a biopsy of the lesion is indicated with anatomopathological study showing the epitheliogiganto cellular granuloma with caseous necrosis [2]. Imaging plays an important role in diagnosis. Conventional radiography is the first exam performed when pulmonary tuberculosis is suspected, but it remains insufficient. Computed tomography is much more sensitive in detecting small, basal, para-mediastinal, or retro-cardiac lesions. It also helps guiding biopsy in atypical form [1], [5].

Pulmonary tuberculosis can take different radiological aspects:

• Centrilobular micronodules that tend to confluent giving a “bud tree” appearance, they are secondary to the bronchogenic dissemination of tuberculosis which is often post primary.
• Alveolar condensation and macronodules that result from the progressive filling of air spaces following the confluence of centrilobular nodules.
• Miliary tuberculosis secondary to hematogenic dissemination.
• Interstitial syndrome.
• Tuberculoma: It is a well-defined rounded or oval lesion in the lung parenchyma. The size is less than 3 cm but can reach up to 5 cm; it is usually located in the upper lobes. Calcifications in the tuberculoma and/or satellite nodules are seen in 30% of cases. Cavitation can be observed in tuberculoma or satellite nodules.
• Cavitary lesion: resulting from excavation of a condensation or nodular lesion. The walls are usually thick and nodular but sometimes thin and regular depending on the evolutionary stage. These lesions can mimic pulmonary cancer especially if the lesion is solitary [1], [3], [5].

Some radiological signs can guide the diagnosis in some cases. In case of pulmonary tuberculosis, the lesions are usually localized in the upper lobes while there is no predilection in lung cancer [2], [3], [4].

Tuberculosis is often associated to necrotic lymphadenopathy, parenchymal infiltrates, centrilobular adjacent micronodules, or pleural effusion. However, the common radiological aspects are a pulmonary nodule or mass with or without pulmonary atelectasis, unresolving pneumonia, pleural effusion, and rib erosion [1], [6].

Cavitation is frequent in tuberculosis and it is centric with regular margins while it is eccentric with irregular margins and radiating strands in malignant mass. Also, if the size of the lesion double in volume after an average of 240 days, it is more likely to be malignant [1].

In our case, the cavitary lesion was isolated, without associated signs, clinical and biological features were not specific, which indicate the biopsy of the lesion.

Pulmonary tuberculosis is characterized by clinical and radiological polymorphism. Solitary pulmonary nodule constitutes a rare presentation. It is difficult to diagnose due to its not evocative aspect, hence, the interest of para-clinical examinations and in some cases a biopsy of the nodule to confirm the diagnosis.