Left lower lobectomy for uncommon endobronchial mucoepidermoid carcinoma in a 15-year-old male

T Patel¹, P Arora¹, A Jakhetiya², A Pandey²,  
¹ Department of Pathology, Geetanjali Medical College and Hospital, Udaipur, Rajasthan, India
² Department of Surgical Oncology, Geetanjali Medical College and Hospital, Udaipur, Rajasthan, India

Correspondence Address:
T Patel
Department of Pathology, Geetanjali Medical College and Hospital, Udaipur, Rajasthan
India

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A 15-year-old male patient presented with a history of chest pain and recurrent lower respiratory tract infections. His thoracic computed tomography (CT) scan demonstrated a soft tissue mass measuring 6.0 cm × 5.7 cm × 4.3 cm involving the left lower lobe of lung with surrounding area of consolidation and ground-glass opacities. On bronchoscopy, a well-defined left endobronchial mass was identified with involvement of left lower lobe of lung. On histopathology, bronchoscopic biopsy was diagnosed as mucoepidermoid carcinoma (MEC) of lung. Taking into consideration the young age of the patient with well-defined tumor and absence of lymphadenopathy on radiology, surgical excision of the tumor was advised. Patient was operated for left lower lobectomy & left station 10 (hilar) lymph nodes excision. Macroscopically, a solid mass was identified arising from the left lower segmental bronchus with infiltration into the lung parenchyma. Cut surface showed grey white, firm area with focal cystic areas filled with mucinous material [Figure 1]. Microscopically, the tumor seemed to be arising from the minor salivary glands of the bronchus and infiltrated the adjacent lung parenchyma. The tumor showed admixture of mucinous, epidermoid & intermediate cells with intracellular and extracellular mucin. Cystic component constituted <10% of the tumor. Mitosis was less than 4/10 HPF. Lymphovascular/perineural invasion and necrosis were absent. The bronchial, vascular and visceral pleural margins were free of tumor. All the resected four left hilar lymph nodes were free of tumor. The histopathological diagnosis confirmed the preoperative diagnosis of endobronchial MEC, low-grade with pTNM staging of pT2N0M0 [Figure 2]. The post-operative CT findings were normal without any significant changes.{Figure 1}{Figure 2}

MEC is generally a common tumor of major and minor salivary glands but primary pulmonary salivary gland tumors are uncommon, and endobronchial MEC accounts for 0.1-0.2% of all neoplasms of respiratory tract.[1] MEC is carcinoma of bronchial gland origin first described by Smetana in 1952.[2] It is the most common salivary gland tumor followed by adenoid cystic carcinoma and epithelial-myoepithelial carcinoma.[3] This tumor is reported to occur in relatively young persons with less than 30 years of age, as was seen in the present case. The common clinical presentation is chest pain, cough, hemoptysis, wheezing, bronchitis and rarely asymptomatic.[4] Chest radiograph shows non-specific findings; therefore, bronchoscopy and CT scan are required for further assessment and differentiation from other conditions.[1] MEC on bronchoscopy usually appears as a polypoidal luminal mass, with mucous filled dilated distal bronchus and surrounding lung parenchyma showing changes of pneumonia. On CT scan, low-grade tumors are usually seen as intraluminal homogeneous masses with or without obstructive change whereas high-grade MEC are lobular, peripheral masses with poorly defined margins.[3] Differential diagnoses of endobronchial mass include benign lesions like pulmonary hamartoma, leiomyoma, pleomorphic adenoma, lipoma, squamous cell papilloma and malignant neoplasms like adenoid cystic carcinoma, bronchogenic adenocarcinoma, squamous cell carcinoma, small carcinoma and carcinoid.[1]

The confirmatory diagnosis is made on the histopathological examination. Grossly, MECs are well-circumscribed solid tumors with grey white to tan cut surface and show few cystic areas, which corresponded with the macroscopic findings of the present case. Histologically, these tumors comprise of mucinous, squamous and intermediate cells and are subclassified as low or high grade based on morphological appearance, cystic areas, necrosis, mitoses, anaplasia, and local invasion. In the present case, necrosis, mitosis and anaplasia were absent.[4]

Low-grade MEC is slow growing and rarely present with metastasis at the first presentation with better survival, whereas high-grade tumors have higher rates of recurrence, parenchymal invasion and mortality. Radical surgical resection with negative margin status is mainstay of the treatment for low-grade pulmonary salivary gland tumors. Various studies have shown low frequency of lymph node involvement ranging from 0% to 20%, thus lymphadenectomy is restricted for the patients with the grossly visible lymph nodes.[5] Although surgical resection remains mainstay of treatment for pulmonary MEC, recently video-assisted thorascopic surgery (VATS) has been used for MEC.[6] In present case, the patient was managed accordingly with lobectomy and dissection of hilar lymph nodes. Use of adjuvant radiotherapy or chemotherapy is regarded ineffective in low grade and margin negative tumors, so was in the present case[3] However, the effectiveness of radiotherapy is considered for unresectable endobronchial MEC in patients with obstructive symptoms.[5]

Endobronchial MEC is an uncommon primary lung malignancy which usually presents with obstructive symptoms or respiratory distress. Clinicians and pathologists should be aware of this rare entity and thorough clinical, radiological and pathological assessment of endobronchial growth is required for definitive preoperative diagnosis of MEC and further management.

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The authors certify that appropriate patient consent was obtained.

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Conflicts of interest

There are no conflicts of interest.

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