Neuroendocrine tumour presenting as a central lung mass with left atrial invasion and superior vena cava compression

Description

Intermediate grade neuroendocrine tumours (NETs) comprise 0.2% of primary lung malignancies, with a wide variety of clinical presentations secondary to tumour size and location.¹ Here, we present a case of a female in her 60s who presented with cough and reflux symptoms for 1 year, with an unintentional weight loss of 30lb in the last 6 months.

After an unsuccessful trial of proton pump inhibitors for presumed gastro-oesophageal reflux disease, her primary care physician ordered a chest X-ray to assess for the presence of a hiatal hernia. Unfortunately, the radiograph showed a large right perihilar mass (figure 1), and a follow-up CT chest scan with contrast noted mass dimensions of 12×11×9 cm with significant invasion of mediastinal structures, superior vena cava compression, invasion of the distal right main pulmonary artery and concern for invasion into the left atrium (figure 2 and figure 3). A transthoracic needle biopsy was performed without complication. Despite extensive counselling on the potential for cardiovascular collapse, the patient declined urgent radiation.

Figure 1.

(A) Chest X-ray of the right middle lobe mass (arrow). (B) Overlaying diagram redemonstrating the right middle lobe mass depicted in grey (arrow). Positional relationship with the mediastinal structures can be seen, with the heart and ascending aorta outlined in red, the superior vena cava in blue and pulmonary arteries in purple.

Figure 2.

(A) Chest CT revealing SVC compression (arrow) and LA involvement (asterisk). (B) Schematic diagram of the mass, whose observed margins are highlighted with a dotted line. Outgrowing of the mass results in malignant SVC compression (arrow), and involvement of the superior left atrium (asterisk). LA, left atrium; SVC, superior vena cava.

Figure 3.

(A) Chest CT demonstrating RIPV tumour invasion (arrow) and RA compression. (B) Schematic diagram redemonstrating invasion of right inferior pulmonary vein, with a sharp cut-off at its expected location (arrow). RA, right atrium; RIPV, right inferior pulmonary vein.

Histology revealed typical carcinoid grade 1 NET cells. An echocardiogram confirmed the presence of tumour within the left atrium (figure 4). CT scan of the abdomen and pelvis with contrast showed no evidence of metastatic disease, but a follow-up positron emission tomography (PET) scan additionally revealed numerous osseus metastases. Given the discrepancy between histological diagnosis and presentation, a left ischial bone biopsy corresponding to an increased area of avidity on PET scan was obtained. Subsequent pathology returned positive for intermediate grade neuroendocrine cells representing an atypical carcinoid tumour. Serum levels of Chromogranin A and serotonin were also found to be elevated. The patient opted to undergo chemotherapy, and completed four cycles of carboplatin and etoposide. A repeat scan demonstrated little improvement in tumour burden, and unfortunately the patient was lost to follow-up.

Figure 4.

(A) Apical trans thoracic echocardiogram view of the tumour protruding into the lumen of the LA (arrow). (B) Schematic diagram highlighting an oval shaped mass inside the LA near the junction of the right pulmonary vein (arrow). LA, left atrium; PA, posterior–anterior; RA, right atrium; RIPV, right inferior pulmonary vein; SVC, superior vena cava.

NETs represent a group of relatively rare malignancies originating from specialised neuroendocrine cells, with common sites including the small intestine and lung (30.4% and 29.8%, respectively).¹ The 2015 WHO Classification of Lung Tumours further divides pulmonary NETs into the following categories: low-grade typical carcinoid, intermediate-grade atypical carcinoid and high-grade small cell and large cell NETs.² Intermediate grade NETs typically present as symptomatic, central lung masses in the fifth and sixth decades of life, with a slight predilection for the male sex. Mean tumour size at the time of diagnosis has been reported as 32.38 mm, with common presenting symptoms including cough, haemoptysis and pneumonia.³ Estimates from the literature suggest up to 50% of intermediate grade NETs present with nodal metastases via the lymphatic system, with distant metastases found in 21%–25% of cases.^{1 4} Surgical resection remains the standard for localised disease, while chemotherapy (carboplatin and etoposide) with or without radiation is recommended for node positive/metastatic disease.⁵ Overall, 5 year survival rates of around 80% have been reported, which unfortunately decrease to 49% in stage IV disease.^{6 7}

The above case constitutes a rare report of a pulmonary intermediate grade NET presenting with aggressive invasion of mediastinal structures and left atrial involvement. Absence of pericardial effusion, wall abnormality or discontinuity suggests haematogenous seeding of the left atrium secondary to pulmonary artery invasion, an unusual phenomenon previously reported in the literature.⁸ Physicians should be aware of the possibility of aggressive behaviours of intermediate grade pulmonary NETs, and they should be considered in the differential diagnoses of patients presenting with central lung masses.

Learning points.

• Pulmonary intermediate grade neuroendocrine tumours comprise a group of rare malignancies that are often detected incidentally on imaging.

• These tumours harbour the potential for aggressive behaviour, including local invasion of mediastinal structures and distant metastases.

• While radiation and/or chemotherapy are suggested for node positive or metastatic disease, treatment plans should always be individualised to the clinical context at hand.

Ethics statements

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