INTRODUCTION: Bronchioloalveolar carcinoma (BAC) is a subtype of pulmonary adenocarcinoma, with growth along intact alveolar septa (lepidic growth pattern). BAC can be classified into mucinous, nonmucinous, and mixed or indeterminate cell types. It has been found that the prognosis of nonmucinous BAC is better than that of mucinous BAC, probably because the mucinous type tends to spread aerogenously and forms infiltrating, multifocal, or satellite tumors. Radiographically, it may present as a solitary peripheral lung nodule, lobar consolidation or multiple pulmonary nodules. We present a unique case of muconous bronchioloalveolar carcinoma presented radiologically as an innumerable sharply defined tiny nodules throughout both lung fields mimicking a miliary infectious etiology and its fulminant course.
CASE PRESENTATION: A 68 year old gentleman with hypertension, diabetes mellitus and a 35 pack year smoking history presented to the emergency room with left sided pleuritic chest pain for the past 1 week associated with mild shortness of breath and nonproductive cough. He denied hemoptysis, fever or chills. He admitted to a 40 pound weight loss over the past 5 months. Physical exam was significant for tachycardia and bilateral rhonchi. Chest radiograph showed miliary like pattern and CT of the chest revealed random distribution of innumerable sharply defined tiny nodules throughout both lungs (Fig 1). Urinary antigen for Histoplasmosis capsulatum, Aspergillosus, HIV test and 3 sets of sputum AFB smears were negative. Diagnostic bronchoscopy revealed no endobronchial lesions with non diagnostic transbronchial biopsies. During this time he progressively became more dyspneic and hypoxic, he was intubated and required ventilaory support. Despite these efforts he continued to have progressive respiratory failure and eventually went into cardiac arrest and expired. Autopsy confirmed extensive bronchioalveolar carcinoma (Fig 2) with metastasis to the mediastinal lymph nodes, liver and adrenal glands.
DISCUSSIONS: BAC was formerly considered a mystery tumor because of its various radiologic, clinical, and cytopathologic manifestations accounting for 3% of all lung malignancies. The solitary nodular form of BAC is the most common and it is seen in 38%, the lobar is seen in 24% of cases, and multilobar condolidation in 31% whereas the diffuse nodular form is the least common presentation and it is reported in 7% of cases. The CT scan appearance of diffuse nodular bronchioloalveolar carcinoma is diverse, and includes poorly or well-defined nodules and multiple poorly defined areas of ground-glass attenuation or consolidation which is not seen in our case. These nodules are usually distributed predominantly in a centrilobular fashion and it is rarely distributed randomly (Fig 1), whereas miliary tuberculosis and pulmonary metastasis usually have a diffuse random distribution. BAC should be considered in the differential diagnosis of solitary or multiple pulmonary nodules and acute or chronic alveolar diseases.
CONCLUSION: The multinodular form of bronchioloalveolar carcinoma should be differentiated from metastatic lung carcinoma, fungal infection, granulomatous disease, lymphoma, and disseminated pulmonary tuberculosis. The diffuse form (multinodules, diffuse, or infiltrative) tends to be relentlessly progressive with a worse prognosis regardless of intervention.
DISCLOSURE: Fadi Al Khankan, No Financial Disclosure Information; No Product/Research Disclosure Information