Authors: Khajotia, Rumi R.; Poovaneswaran, Sangeetha.
Background: The ‘tree-in-bud’ pattern is an appearance typically seen on HRCT or thin-section computed tomography (CT) chest scan. It is characterized by small centrilobular nodules of soft-tissue attenuation connected to multiple branching linear structures of similar caliber which originate from a single stalk. Initially described in cases of endobronchial spread of Mycobacterium tuberculosis , it has subsequently been observed as a manifestation of a variety of entities, including idiopathic disorders (obliterative bronchiolitis and panbronchiolitis), infections (bacterial,viral, fungal and parasitic) involving peripheral airways, immunologic disorders, connective tissue disorders, aspiration, inhalation, congenital disorders and pulmonary intravascular tumor emboli (carcinomatous endarteritis). In patients with pulmonary tuberculosis, the tree-in-bud pattern is believed to be a characteristic CT feature of active endobronchial spread and can be found in 72% of patients with active disease. We report here, the case of a young woman with breast carcinoma who developed pulmonary tuberculosis while on chemotherapy and whose HRCT chest scan showed characteristic ‘treein-bud’ opacities.
Case presentation: A 42-year-old female presented with a lump in her left breast. There were no other significant symptoms. On examination, a 4 cm lump was palpable in the upper outer quadrant of the left breast. Mammography confirmed the presence of a 4 cm mass with spiculate margins and distorted architecture. Core biopsy was performedwhich confirmed the presence of a grade II infiltrating ductal carcinoma. A left-sided modified radical mastectomy was performed with level II axillary clearance. Nine out of sixteen nodes from the axillary clearance showed presence of metastatic deposits. She was subsequently started on 3 weekly cycles of chemotherapy which included 5-flurouracil, epirubicin and cyclophosphamide. Five months later, the patient presented with dry cough, low-grade fever with an evening rise of temperature, generalisedweakness and loss of appetite. She had lost 4 kilograms of weight in the last 3 months. On examination, a few coarse crepitations were heard over the mid-zone of her right lung. Chest radiograph was unremarkable and the total white cell counts were normal (7.6×109 cells/ L). An HRCT chest scan was done. It showed the presence of peripheral, small, centrilobular, well-defined nodules of soft-tissue attenuation connected to linear, branching opacities that had more than one contiguous branching site originating from a single stalk, resembling a typical ‘tree-in-bud’ pattern. No mediastinal or hilar gland enlargement was noted and no other lesions were seen. A differential diagnosis of pulmonary tuberculosis, pulmonary infections (bacterial, viral, fungal and parasitic) involving peripheral airways and pulmonary intravascular tumor emboli (carcinomatous endarteritis) was considered.
Initial examination of three early morning sputum samples was negative for acid-fast bacilli (AFB) and therefore pulmonary intravascular tumor emboli were considered a likely possibility. However, subsequently, induced sputum samples were collected using 3% hypertonic saline solution delivered by an ultrasonic nebulizer (Devilbiss Ultraneb 99, PA, USA). Three early morning induced sputum samples were collected on consecutive days. On smear examination, the samples were positive (+++) for AFB. Subsequently, culture of the sputum samples confirmed presence of live AFB. The sputum samples were negative for malignant cells and bacterial culture.
Tests for rheumatoid arthritis and Sjogrens syndrome too were negative.
In view of her history and investigative findings, a diagnosis of pulmonary tuberculosis manifesting as ‘tree-in-bud’ opacities was made and the patient was started on anti-tuberculous treatment. After 2 months of treatment, the cough and fever had subsided, her appetite had improved and she had gained 3 kgs of weight.
Document Type: Research Article