Pathologic findings:
| Figure 1: Low power view of bronchial biopsy. | Figure 2: Hgh power view of bronchial biopsy. |
The bronchial biopsy show a fragment of bronchial mucosa and several
fragments of tumour tissues with an infiltrative pattern. However, the
tumour cells have small hyperchromatic nuclei which are not very pleomorphic
and show no anaplastic features. The mitotic rate is very low. These cells
form small aggregates and cords with some glandular lumen. Large cytoplasmic
vacuoles are seen in some tumour cells. In addition, intercellular bridges
suggestive of squamous differentiation are also seen. These features favour
a mucoepidermoid carcinoma as the most probable tumour type.
| Figure 3: Tumour occluding bronchus | Figure 4: Gross appearance of tumour | Figure 5: Whole mount section of tumour | Figure 6: Low power view and bronchial mucosa |
| Figure 7: Low power view and bronchial wall | Figure 8: Medium power view | Figure 9: High power view. |
Consists of the left lung weighing 185 gm and measuring 14.0x10.0x4.0 cm in dimension. It includes a stump of the main bronchus which had already been partially cut. This shows an ovoid tumour comletely occluding the lumen. Abundant pale yellowish and mucoid secretions fill up the lumen behind the tumour and the rest of the lung parenchyma appear collapsed. However, no tumour mass or suppuration is found in the lung parenchyma. The bronchial tumour has a smooth, mucoid surface and measures 2.0x1.5x1.0 cm in dimension. It does not appear to involve the bronchial margin grossly. No enlarged node is found in the hilum.
Sections show a polypoidal tumour arising from the superficial parts of the bronchial mucosa. It is mostly covered by an intact bronchial epithelium with only focal ulceration. The tumour consist of groups of glandular structures accompanied by mucus secretion. These glands are also accompanied by squamoid differentiation in some tumour cells characteristic of muco-epidermoid carcinoma. The degree of glandular formation is extensive, indicating a well differentiated carcinoma. The tumour base is 0.8 cm from the bronchial surgical margin, which is not involved. At the base, some residual benign bronchial glands accompanied by inflammation are seen. The cartilaginous layer of the bronchus is not infiltrated. Several peribronchial lymph nodes show no evidence of tumour metastasis. The adjacent smaller bronchi also show no significant pathology. The lower lobe lung parenchyma contains areas of pneumonia with fibrosis and collapse. Subcarinal lymph node - No tumour found.
Pathologic Diagnosis:
Left lung - Muco-epidermoid carcinoma of bronchus. Bronchial surgical margin free of tumour. All lymph nodes examined are not involved.
Pathologist Comments:
The usual carcinomas (small cell and non-small cell carcinomas) of the lung are believed to arise from reserve cells at the basal layers of the bronchial surface epithelium. In contrast, there are a variety of much less common carcinomas which are believed to originate from submucosal bronchial glands. These are not related to smoking and are analogous to salivary gland tumours having the same name. Most are located within the main bronchi. In the past, they were grouped under 'bronchial adenoma' because of their lower grade histological appearance, a practice which had now been abandoned.
Mucoepidermoid carcinoma of the lung can be divided into low-grade and high-grade varities, based mainly on the degree of glandular formation. The malignant potential is lower than those of usual carcinomas and are characterized mainly by local invasion.
The tumour in this patient has extensive glandular formation indicating a low grade tumour. In addition, it had not involved the bronchial surgical resection margin and had not infiltrated beyond the bronchial wall. All lymph nodes examined were not involved and all these factores are indicative of a good prognosis.
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