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A 66-year-old female diagnosed with atypical carcinoid tumor
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A 66-year-old woman in stable health was sent for a routine chest CT scan in April 2003 because of her history as a former heavy smoker.
The CT scan revealed a 1.5 cm suspicious nodule in the right lung apex.
The woman underwent a video-assisted thoracoscopic surgery with a wedge resection of the right upper lobe nodule. The frozen section was consistent with small cell lung cancer.
Figure 1. A chest CT axial image (lung windows) from 2003 demonstrates a 1.5 cm lobulated nodule at the medial right upper lobe.
Final pathology results — which followed a special stains study and a second opinion at Memorial Sloan-Kettering Cancer Center — were consistent with an atypical carcinoid tumor of the lung.
Figure 2. A recent chest CT axial image (soft tissue windows) demonstrates a right hilar mass (arrow), partially calcified and now compressing the right middle lobe bronchus.
Metastatic workup at that time in the form of bone scan and brain MRI were negative. She underwent completion right upper lobectomy and thoracic lymphadenectomy. On the final pathology report, two of the lower paratracheal lymph nodes were positive for atypical carcinoid tumor. No additional treatment was recommended at that time.
Figure 3. In-111 pentetreotide (octreoscan) anterior and posterior whole-body images show normal uptake in the liver, spleen, gastrointestinal tract and genitourinary tract.
Since then, the patient has been followed with CT scan of the chest every 6 to 12 months.
Figure 4. A Tc-99m MDP bone scan with anterior and posterior whole-body images show degenerative changes with no evidence of skeletal metastases.
In August 2012, the patient — now aged 75 years — presented with persistent back pain for 2 weeks. The pain was so severe that it required hospitalization. MRI showed lesions highly suspicious for diffuse lytic metastases in the thoracic and lumbar spines, sacrum and iliac crest.
Figure 5. A PET FDG maximum-intensity projection image shows multiple foci of abnormal hypermetabolism in the right hilum and mediastinum with maximum standard uptake value up to 4.1, corresponding to soft tissue mass and adjacent lymph nodes.
A CT-guided biopsy of L1 vertebral body confirmed the diagnosis of metastatic atypical carcinoid tumor.
Figure 6. Sagittal T1 (left) and T2 (middle) weighted MRI images of the thoracic spine demonstrate diffuse multilevel metastatic disease. A CT reconstructed sagittal image (right, bone window) does not reveal corresponding abnormalities.
Further workup in the form of whole body PET/CT and whole-body octreoscan were negative and failed to demonstrate any imaging correlates of the lesions clearly seen on the MRI.
The patient currently is being evaluated for possible initiation of palliative chemotherapy.
Discussion
Carcinoid tumors have an annual estimated incidence of two to four per 100,000, but the true incidence probably is higher at eight per 100,000 population, as evidenced by autopsy data.
Figure 7. MRI (T2, left), CT (bone window, right) and fused PET/CT axial images at the L1 vertebral body demonstrate that the conspicuous signal abnormality on MRI (arrow) does not have a CT correlate. There is only mild, indistinct FDG avidity (standard uptake value <3).
Source: Images courtesy of M. Ghesani, MD, reprinted with permission.
Bronchial carcinoid tumors account for approximately 1% to 2% of all lung malignancies in adults and roughly 20% to 30% of all carcinoid tumors.
The most common histologic subtype of bronchial carcinoids is typical, or well differentiated, and it comprises 75% of all tumors. The atypical carcinoids are more peripheral in location and occur more commonly in older patients and smokers. They are aggressive tumors, and 30% to 50% can spread to the mediastinal nodes.
The majority of bronchial carcinoids present in a manner that is similar to other primary lung malignancies, with cough or hemoptysis, or as an asymptomatic peripheral pulmonary nodule.
CT is the most useful initial imaging procedure. MRI generally does not provide more information than can be obtained by high-resolution CT, but dynamic contrast-enhanced MRI may be helpful to differentiate a small contrast-enhancing peripheral carcinoid from pulmonary vessels.
Generally, osteoblastic metastatic lesions are better appreciated on the bone scans and CT scans. Marrow-based osteolytic lesions — as in our patient — are better appreciated on MRI and fluorodeoxyglucose (FDG)-PET scans. However, a subset of neuroendocrine tumors and well-differentiated tumors may not demonstrate FDG hypermetabolism and, therefore, can be false negative on FDG-PET scans. This is a likely explanation of the unimpressive PET findings in our patient.
Approximately 60% of atypical carcinoids express somatostatin receptors. However, not all tumors that express somatostatin receptors by immunohistochemistry will be positive on somatostatin receptor scintigraphy or octreoscan.
The diagnosis generally is confirmed either by bronchoscopic biopsy (for central lesions) or by transthoracic needle biopsy for peripheral lesions. Pulmonary carcinoids generally are staged using the TNM classification for bronchogenic lung carcinomas.
Surgery is the only curative option for both typical and atypical bronchial carcinoid tumors. Between 5% and 20% of typical carcinoids and 30% to 70% of atypical carcinoids metastasize to lymph nodes. A complete mediastinal lymph node sampling or dissection at the time of initial treatment is indicated, with surgical resection of nodal metastasis whenever feasible.
Metastatic involvement of mediastinal lymph nodes does not preclude a full surgical resection or cure. The role of adjuvant therapy after complete resection of a bronchial carcinoid is undefined and controversial. It is not recommended by the consensus-based guidelines from the North American Neuroendocrine Tumor Society, but the National Comprehensive Cancer Network suggests the use of chemotherapy with or without radiation therapy for resected stage II or III atypical carcinoids and for stage IIIB typical carcinoids.
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For more Information:
Munir Ghesani, MD, is an attending radiologist at St. Luke’s-Roosevelt Hospital Center and Beth Israel Medical Center, an associate clinical professor of radiology at Columbia University College of Physicians and Surgeons, and a HemOnc Today section editor. He may be reached at Department of Radiology, Beth Israel Medical Center, First Avenue at 16th Street, New York, NY 10003; email: mghesani@chpnet.org.
Abdelaziz Elhaddad, MD, is an oncology fellow at St. Luke’s-Roosevelt Hospital Center.
Michael Starc, MD, is a radiology resident at St. Luke’s-Roosevelt Hospital Center.
Disclosure: Ghesani, Elhaddad and Starc report no relevant financial disclosures.