ECR 2002 COD #7: Bronchioloalveolar carcinoma of the lung

Clinical History

The patient was admitted to hospital with cough and progressive dyspnoea. Large amounts of mucous sputum were expelled during major cough attacks. There was no history of drug ingestion and no significant past medical history. Physical examination, including appropriate laboratory tests and pulmonary function tests, revealed diffuse pulmonary parenchymal involvement. Bronchoscopy showed normal major bronchi. Bronchoalveolar lavage was negative for malignancy.

Imaging Findings

The patient was admitted to hospital with cough and progressive dyspnoea. Large amounts of mucous sputum were expelled during major cough attacks. There was no history of drug ingestion and no significant past medical history. Physical examination, including appropriate laboratory tests and pulmonary function tests, revealed diffuse pulmonary parenchymal involvement. Bronchoscopy showed normal major bronchi. Bronchoalveolar lavage was negative for malignancy.

On chest x-ray (Fig. 1), bilateral shaggy multiple pulmonary nodular densities, of various dimensions, producing confluent infiltrates were seen scattered in the middle and lower lung fields. There was no hilar enlargement or pleural effusion. On CT scanning (Fig. 2), multiple confluent nodules were seen in both upper lobes and in the right middle lobe. Ill-defined areas of consolidation were visible in both lower lobes. Opacified normally branching vessels were clearly visible within the low relative attenuation of consolidations.

Four months later repeat chest x-rays (Fig. 3) demonstrated grouping of "acinar" shadows, with increased lung infiltration and one year after initial presentation chest x-rays (Fig. 4) demonstrated considerable advance of the disease with extensive infiltrative lesions, in both lower and middle lung fields.

CT scans taken one year after initial presentation (Fig. 5) showed an increase in number and dimension of shadows throughout both lungs with radiolucencies in some of the nodules. There was no lymph node involvement or pleural effusion.

A chest x-ray (Fig. 6) taken 14 months after initial presentation showed diffuse bilateral involvement with fluffy, extensive confluent infiltrates bilaterally.

Discussion

Bronchioloalveolar carcinoma (BAC) is a variant of adenocarcinoma that constitutes about of 2-10% of all primary lung carcinomas. Of all cases of BAC 30-50% occur in women, with no other organ involvement . Usually there is no association with smoking. There is an increased incidence of this malignancy among patient with previous pulmonary scarring, fibrosis, diffuse interstitial inflammation or scleroderma. BAC begins as a single peripheral, well-differentiated, low-grade neoplasm that tends to spread by infiltrating contiguous lung parenchyma, using the lung structure as stroma. Aerogeneous spread of tumour cells to other parts of the lung results in diffuse pulmonary disease. Distant metastases occur via lymphatic and haematogenous routes. In the early unifocal stage the patient has no symptoms at all, or complains only of mild cough with bronchorrhoea. Abundant mucoid expectoration can produce hypovolaemia and electrolyte depletion, a symptom that indicates extensive lung disease.

Potential cells of origin are mucin-secreting bronchial epithelial cells, non-ciliated secretory bronchiolar cells, and type 2 alveolar epithelial cells. Two general gross pathologic types are described: a tumour-like or nodular form and a diffuse form. The first form tends to remain localised and has an excellent prognosis after resection, while the second form represents an aggressive malignancy with poor prognosis regardless of surgery.

Radiographically, BAC may have one of the following three patterns: solitary nodule or mass, localised area of parenchymal consolidation and multicentric or diffuse disease. X-ray films, in the first pattern, may show a non-specific peripheral well-circumscribed coin lesion, occasionally producing puckering of the pleura. Irregular margins are present in 73% of cases. This lesion often grows very slowly and can be relatively stable for as long as 5-10 years. Air bronchogram or pseudocavitation due to dilatation of intact air spaces from desmoplastic reaction, bronchiectasis and focal emphysema may be present in 60% of cases. In the second pattern, when the disease occurs locally, a lung segment or an entire lobe may become consolidated, resembling pneumonia. Alternatively, in the third pattern, when there is bronchogenic spread of the disease, a multinodular pattern, resembling haematogenous metastases, can be seen. Air-space consolidation due to mucous secretion may affect both lungs. Hilar and mediastinal lymph node involvement has been observed in 18% of patients. Pleural effusion is present in 8-10% of cases. True cavitations in BAC are uncommon and have been observed in 7% of cases. In conclusion, radiographically, the disease may resemble pyogenic or granulomatous inflammation, vascular, or tumoral disease.

Cytological examination of the sputum leads to the correct diagnosis in only about one-third of cases. Final diagnosis of the disease is based on histological examination of tissue obtained by transbronchial or open lung biopsy.

The condition of this patient was further aggravated despite the fact that adequate treatment was provided immediately after specific diagnosis. This report shows the radiological findings over 14 months in a case of BAC of the lung with no adenocarcinoma elsewhere in the body.

Differential Diagnosis List

Final Diagnosis

Bronchioloalveolar carcinoma of the lung

URL:	https://www.eurorad.org/case/1389
DOI:	10.1594/EURORAD/CASE.1389
ISSN:	1563-4086