A case of pulmonary typical carcinoid with an extensive oncocytic component showing intense uptake of FDG

Does 68Ga-DOTA-NOC-PET/CT impact staging and therapeutic decision making in pulmonary carcinoid tumors?

OBJECTIVE

Purpose of this study was to assess the utility of Ga-DOTA-NOC-PET/computed tomography (CT) (Ga-NOC-PET) in tumor detection, pathological differentiation and baseline staging of pulmonary carcinoids as well as to study its impact on therapeutic decision making.

PATIENTS AND METHODS

Patients who underwent a Ga-NOC-PET for initial evaluation of bronchopulmonary carcinoid tumors from August 2014 to December 2019 were included. Detection rate of Ga-NOC-PET for the primary lesion was calculated by visual estimation of tracer uptake as per Krenning score. SUVmax of typical and atypical carcinoid tumors was measured and difference compared using nonparametric statistical tests. Proportion of patients with distant metastases was also calculated and its impact on intended treatment was assessed.

RESULTS

Imaging, histopathology and treatment details of 119 patients were available for analysis. Majority of tumors had an endobronchial location (74.7%) and showed histopathologic features of typical carcinoid (82.3%). Ga-NOC-PET showed a detection rate/sensitivity of 92.4%. Oncocytic variant on histopathology and smaller tumor size accounted for majority of negative results. Typical carcinoids showed significantly higher SUVmax than atypical tumors (median SUVmax 38.4 vs. 15.7, P = 0.002). Metastases to distant sites outside the thorax were seen in 14 patients (11.7%), primarily in liver and bones changing the intent of treatment from surgery to systemic therapy.

CONCLUSION

Ga-NOC-PET detects asymptomatic distant metastatic disease in a sizeable number of patients (11.7%) with pulmonary carcinoid and thus contribute to clinical management by precluding futile surgeries. It shows a high sensitivity for tumor detection and can help differentiate between typical and atypical carcinoid variants by virtue of their variable tracer uptake. PET/CT using Ga-labeled DOTA peptides should be an integral part of diagnostic workup of patients with lung carcinoid.

Oncocytic Adrenocortical Neoplasm with Concomitant Papillary Thyroid Cancer

Adrenal oncocytoma (AO) is an extremely rare adrenocortical neoplasm and little is known about its malignant potential, secretory properties, and hereditary origin. We present the case of a benign AO with concomitant incidentally found papillary thyroid cancer (PTC) and review similar cases in the literature. Immunohistochemistry and next-generation sequencing (NGS) were performed. A 66-year-old women was incidentally found to have a large, androgen-secreting right adrenal mass. ¹⁸F-Fluorodeoxyglucose positron emission tomography showed intense uptake (SUV_max 88.7) of this mass and found a hypermetabolic right thyroid mass. Open adrenalectomy was performed for this highly suspicious adrenal mass. Histopathology revealed benign AO that was BRAF^V600E negative, with low Ki-67, and no somatic mutation found on NGS. Thyroidectomy revealed invasive, BRAF^V600E-positive PTC. At 6 months follow-up, androgen levels returned to normal, and no recurrence was seen on imaging. To our knowledge, this is the first report of an androgen-secreting AO with concomitant PTC. Possibly the simultaneous discovery of two independent neoplasms was observed. In conclusion, this case highlights that care should be given to exclude concomitant neoplasms. Long-term and regular imaging with biochemical follow-up is warranted, since the outcome and clinical behavior of AO remains uncertain.

18F-FDG PET/CT Diagnosis of Bronchopulmonary Carcinoids Versus Pulmonary Hamartomas

PURPOSE

Radiological characterization of pulmonary tumors may be difficult and invasive. Needle biopsy may produce false-negative results. 18F-FDG PET/CT is an established noninvasive procedure for lung tumor characterization and staging. This study was aimed at differentiating bronchopulmonary carcinoids from hamartomas and typical from atypical bronchopulmonary carcinoids by means of 18F-FDG PET/CT.

PATIENTS AND METHODS

In a retrospective analysis of 118 patients, with surgically resected pulmonary carcinoid tumors and hamartomas, 87 of those selected had also undergone 18F-FDG PET/CT preoperatively and constituted the study population. To better assess the tracer accumulation, especially in small lesions, the 18F-FDG uptake (SUV) in the tumors was corrected for partial volume effect by applying recovery coefficients corresponding to the respective various specific tumor volumes, as extrapolated from those obtained from experiments in a NEMA phantom.

RESULTS

The SUVmax was higher in the pulmonary carcinoids (mean, 3.9) than in the hamartomas (mean, 1.4; P ≤ 0.00001) and higher in the subgroup of peripheral carcinoids than in hamartomas (P ≤ 0.00001). The SUVmax was similar for the atypical and typical carcinoids, 5.0 and 3.8, respectively, because of the large variation in the data (P = 0.11).

CONCLUSIONS

Using PET measurements of the 18F-FDG uptake (SUVmax) in the tumors, corrected for partial volume effects, it was possible to differentiate the carcinoids from the hamartomas, but the clinically more aggressive atypical carcinoids could not be differentiated from the typical carcinoids.

Sinonasal oncocytic Schneiderian papilloma accompanied by intravascular lymphoma: A case report on FDG-PET/CT imaging

INTRODUCTION

F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is useful for the staging and assessment of treatment response in patients with lymphoma. Occasionally, benign lesions demonstrate avid FDG uptake and result in false positive findings.

CASE

We report the case of an 82-year-old man presenting with cutaneous lesions, which were histopathologically diagnosed as intravascular lymphoma. FDG-PET/CT for staging demonstrated an FDG-avid mass extending from the right maxillary sinus to the nasal cavity, moderate uptake in the adrenal glands, mild uptake in the knee and the foot, and faint uptake in the skin and subcutaneous tissue of the legs. He subsequently underwent biopsy of the paranasal mass, which was diagnosed as oncocytic Schneiderian papilloma without lymphoma invasion. Glucose transporter (GLUT) 1 staining was highly positive in the papilloma cells, resulting in high FDG avidity. After completion of chemotherapy, the abnormal FDG uptakes in the skin, soft tissue, and adrenal glands disappeared on PET/CT. However, avid FDG uptake persisted in the sinonasal Schneiderian papilloma for 15 months before regression.

CONCLUSION

Benign tumors with oncocytic components may show avid FDG uptake. Therefore, correct diagnosis of oncocytic Schneiderian papilloma on FDG images is difficult when other accompanying malignant tumors, especially lymphoma, are present. If post-therapeutic PET/CT images show a discordant lesion, oncocytic tumors, albeit uncommon, should be considered in the differential diagnoses.

Bronchogenic carcinoid tumours that are 18F-fluorodeoxyglucose avid on positron emission tomography

OBJECTIVES

Bronchogenic carcinoid tumours are widely cited as non-fluorodeoxyglucose (FDG) avid. However, three case reports of FDG-avid bronchogenic carcinoid tumours have been published, leading to speculation as to which clinicopathological factors may be associated with increased activity on FDG-positron emission tomography. We reviewed a series of cases from our institution and compared them with the available reports in the literature, to attempt to identify the factors associated with FDG avidity in bronchogenic carcinoids.

METHODS

We performed a single-institution retrospective review.

RESULTS

One patient was identified at our institution who had a typical carcinoid tumour with a standardized uptake value (SUV) of 26, oncocytic features on histology and positive staining for glucose transporter 1 (GLUT1). Three additional patients were identified in the literature with typical bronchogenic carcinoids with SUVs of 39, 38 and 33. Two of these tumours stained positive for GLUT1, and the remaining patient was not tested. Two of these patients had oncocytic features on histology, and results on the remaining patient are not reported. Additionally, 4 patients at our institution were identified with bronchogenic carcinoids with average SUV of 2.6. All were GLUT1 negative, and none had oncocytic features. In the reported literature, excluding the four most FDG-avid tumours described above, atypical carcinoids had a higher mean SUV than typical carcinoids (5.7 vs 3.4, P = 0.02), but size was not correlated with SUV (r = 0.7, P = 0.3).

CONCLUSIONS

FDG uptake is commonly associated with worse prognosis in malignancy; however, bronchogenic carcinoids, particularly oncocytic typical carcinoids, are a possible source of extremely high SUVs on FDG-PET.