Pulmonary blastoma: a case report and review of the literature

Abstract

Background: Pulmonary blastomas are a rare aggressive neoplasm comprising 0.25-0.5% of all primary lung tumors and portend a poor prognosis. They display a biphasic histology with mesenchymal and epithelial components. Historically, the term pulmonary blastoma had included both pure fetal adenocarcinomas, pleuropulmonary blastomas as well as the classic biphasic blastomas. However recent World Health Organisation re-classifications separated well-differentiated fetal adenocarcinomas and pleuropulmonary blastomas from the biphasic tumours.

Case presentation: We present a case of a systemically well 67-year-old Caucasian male who presented with haemoptysis. Investigations confirmed the presence of a large right-sided lung mass and biopsy identified non-small cell carcinoma. The resected tumour was markedly necrotic revealing a biphasic pattern. It was composed of malignant glandular tissue with sub-nuclear vacuoles, associated with a pleomorphic stromal malignant blastematous component, characteristic of classic biphasic pulmonary blastoma.

Conclusion: We present a case of a classic biphasic pulmonary blastoma, a rare lung cancer occurring at an earlier age and portending to poorer prognosis than other more common lung cancers. Given the small number of cases and recent re-classification, interpreting the published epidemiology and clinical features of this disease is difficult. Many earlier reports may have included fetal adenocarcinomas (in particular high grade variant), which need to be considered when discussing treatment and prognosis with newly-diagnosed patients. Much could be gained from a central registry of individual experiences to improve our understanding of this rare lung cancer.

Figure 1

Large right-sided mass with characteristic hilum overlay sign.

Figure 2

A positron emission tomography-computed tomography (PET-CT) demonstrated increased fludeoxyglucose uptake within the mass, standardized uptake value (SUV max22.1) and no evidence of nodal involvement or distant metastases.

Figure 3

Histological analysis of the tumour. a. Malignant glandular tissue with sub-nuclear vacuoles. b. Pleomorphic stromal malignant blastematous component. c. The malignant glandular component was diffusely positive for the epithelial marker Cam 5.2. d. Positive for TTF-1 and negative for vimentin. e. The stromal blastematous malignant component showed reverse expression. f. The protein beta-cathenin was observed in both components.