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it is composed of mucus - containing acini - lined by cuboidal cells without pleomorphism .
the lesion is classified as a benign epithelial tumor of the lung , among the salivary gland - type adenomas .
the main differential diagnoses are a low - grade mucoepidermoid carcinoma , primary adenocarcinoma , and benign adenomatous lesions of lung .
a 32-year - old kashmiri woman was referred to our hospital with chief complaints of hemoptysis , cough , and fever of 2-year duration .
laboratory investigations revealed hemoglobin of 9.0 g / dl with normal total leucocyte and platelet counts .
contrast - enhanced computed tomography ( cect ) chest showed a well - circumscribed homogeneously enhancing mass lesion in the apical segment of left lower lobe occluding the left lower main bronchus .
there was no evidence of any calcification or necrosis on ct scan [ figure 1a ] .
fiberoptic bronchoscopy done revealed a polypoidal growth arising from the lower lobe - left causing occlusion of left main bronchus and suggested the possibility of a carcinoid tumor .
finally preoperative diagnosis of carcinoid tumor arising from the left lower lobe bronchus involving the apical segment of the lower lobe was made .
a left lower lobectomy was performed via left posterolateral thoracotomy and specimen was sent for histopathological examination .
macroscopic examination of the resected specimen revealed a whitish solid mass , 5.5 cm in maximum diameter , arising close to the bronchus and compressing the adjacent lung parenchyma .
microscopically , the tumor was well circumscribed , lined by respiratory epithelium , and consisted of numerous irregularly arranged cysts , tubules , and glands lined by bland columnar , cuboidal , or flattened , mucus secreting cells .
tumor was found projecting into the bronchial lumen , however , not invading the underlying cartilage [ figure 2a and b ] .
the intervening stroma consisted of delicate connective tissue and lymphoplasmacytic infiltrate [ figure 2c ] .
taken together , these observations led us in making a diagnosis of a bronchial mucous gland adenoma .
( a ) cect chest showing a well - circumscribed homogenously enhancing mass lesion in the apical segment of left lower lobe , ( b ) cut surface of mucous gland adenoma showing mucoid gelatinous surface with numerous small cysts of variable sizes .
tumor is arising from the bronchus and compressing the adjacent lung parencyma ( a ) tumor is lined by respiratory epithelium and consists of numerous irregularly arranged tubular glands ( h and e , 20 ) , ( b ) photomicrograph showing tumor projecting into the bronchial lumen without invading the underlying cartilage ( h and e , 20 ) , ( c ) the glands are lined by single layer of mucous secreting tall columnar cells and the interveining stroma shows lymphoplasmacytic infiltrate ( h and e , 20 ) , ( d ) glands showing alcian blue positivity ( periodic acid - schiff and alcian blue stain , 40 ) , ( e ) epithelial cells showing ttf-1 negativity ( ihc , 40 )
mucous gland adenoma is a rare benign tumor originating from the mucous secreting glands of the larger airway mucosa .
this tumor was first reported in 1882 by muller as a pathologic entity separate from carcinoma of the lung and was first named bronchial adenoma arising from mucous gland .
the majority of the cases are seen in the bronchus , but it has also been described in the trachea or peripheral airways . the tumor occurs with equal frequency in men and women and at any age ( mean 52 ) , including children .
most commonly reported symptoms are cough , fever , and recurrent pneumonia and these are the result of bronchial obstruction by the tumor
. the clinical presentation may be mistaken for asthmatic disorders or chronic obstructive pulmonary disease for long periods of time .
other nonspecific observations such as a chronic cough , unilateral wheezing , hemoptysis , or pulmonary infections can also be present for a long time before a correct diagnosis is made . in this case , the patient had symptoms since 2 years and was wrongly diagnosed as tuberculosis and treated with att for 6 months .
there is nothing on bronchoscopic findings that would distinguish mucous gland adenoma from other neoplastic and non - neoplastic bronchogenic lesions , although the presence of surface microcysts and a gelatinous coating over the surface of tumor is more in keeping with mucous gland adenoma .
pulmonary adenomas are uncommon and can be classified as alveolar adenoma , papillary adenoma , mucinous cystadenoma or adenomas of the salivary - gland type , which include pleomorphic adenoma , monomorphic adenoma , myoepithelioma , and mucous gland adenoma .
histological differential diagnoses include low - grade mucoepidermoid carcinoma , primary adenocarcinoma as well as the benign adenomatous lesions , glandular papilloma , papillary adenoma , alveolar cell adenoma , and mucinous cystadenoma .
the mucoepidermoid carcinoma is a rare malignant tracheobronchial tumor but encountered more frequently than the bronchial mucous gland adenoma .
an adenocarcinoma shows the typical features of malignancy , such as cytological atypia , mitoses , and an infiltrative growth pattern along with strong ttf-1 immunopositivity in the neoplastic glands .
immunohistochemically , a bronchial mucus gland adenoma usually expresses high molecular weight keratins , but it is negative for ttf-1 .
the glandular papilloma has an endobronchial growth pattern and typical fibrovascular cores , lined by ciliated or nonciliated columnar cells and a varying proportion of cuboidal and goblet cells .
mucinous cystadenoma of the lung is a benign lesion histologically similar to the bronchial mucous gland adenoma .
however , it occurs in the peripheral pulmonary parenchyma and is a true mucin - filled cyst lined by mucous epithelium , with variable expression of ttf-1 antigen .
a papillary adenoma , however , consists of fibrovascular cores lined by cuboidal or columnar epithelium and it is positive for ttf-1 , whereas alveolar adenomas are well - circumscribed unencapsulated multicystic masses with ectatic spaces lined by cytologically bland flattened , cuboidal , and hobnail cells that show positivity with broad spectrum keratins , ttf-1 , and cea . mucous gland adenoma is a benign tumor and does not recur or metastatise .
the treatment of choice is the complete excision of the mucous gland adenoma involving the bronchus or pulmonary segment or lobe .
benign glandular tumors of the tracheobronchial tree remain out of the limelight of pulmonary medicine .
nevertheless , many patients with mucous gland adenoma go on for years with repeated hemoptysis and recurrent pneumonias prior to the diagnosis .
this observation gives credence to the necessity of an in - depth lung workup in patients presenting with signs of respiratory tract infections and such unusual differential diagnoses should be considered .
mucous gland adenoma of the lung is an uncommon benign tumor that histologically resembles the mucus - secreting component of tracheobronchial gland . 
 the majority arises within the main , lobar , or segmental bronchi but parenchymal involvement had also been reported . 
 we herein present a case of mucous gland adenoma arising from the left lower lobe bronchus . 
 the 32-year - old female presented with massive hemoptysis , productive cough , and dyspnoea and was clinically misdiagnosed as tuberculosis . 
 radiology proved to be inconclusive . 
 this case highlights the importance of a complete lung work up in patients presenting with signs of respiratory tract infections .