Classic biphasic pulmonary blastoma (CBPB): a rare primary pulmonary malignancy

Abstract

Classic biphasic pulmonary blastoma (CBPB) is a very rare primary pulmonary malignancy with distinctive clinical and pathological features. Usually CBPB presents with either non specific symptoms or is diagnosed incidentally. Histologically CBPB is composed of a mixture of malignant epithelial and stromal cells resembling fetal lung tissue. Surgical resection is the mainstay of treatment with further chemotherapy or radiotherapy on a case-by-case basis. However, due to its rarity, no definite treatment guidelines are available. CBPB overall has a very poor prognosis with a 5-year survival rate of only 15%. Our patient presented with cough and haemoptysis. Her chest radiograph demonstrated a large right-sided lung mass. Further investigations included CT, CT-guided biopsy and PET CT which were discussed at multidisciplinary team meetings. The patient then underwent complete surgical excision. We report this rare malignancy with radiological and pathological features, comparing them with previously reported cases.

Keywords: cardiothoracic surgery; lung cancer (oncology); pathology; radiology.

Figure 1

On the left, chest radiograph from July 2013 with no evidence of mass. In the middle, chest radiograph from September 2020 showing circumscribed mass in the right upper lobe (red arrow). On the right, chest radiograph from early November 2020 with significant increase in right upper lobe mass size (red arrow).

Figure 2

Coronal CT showing 135 mm size right upper lobe mass with indentation and leftward displacement of mediastinal structures.

Figure 3

Sagittal CT scan showing right upper lobe mass with venous tumour thrombus (white arrow).

Figure 4

Axial PET CT image showing peripherally avid right upper lobe mass (white arrow). PET, Positron Emission Tomography.

Figure 5

Photomicrograph from the surgical resection specimen showing the tumour to have a biphasic morphology. parts of the tumour are composed of tall columnar cells forming well defined glandular structures (A+arrows). Interspersed with these are more diffuse sheets of smaller, rounder cells with a more primitive undifferentiated morphology (B) these morphological features are in keeping with this being a carcinoma with sarcomatoid features and are in keeping with a pulmonary blastoma. (H&E stain, original magnification ×100).