ABSTRACT
INTRODUCTION: We assessed the impact of [(18)F]-fluorodeoxyglucose (FDG)-positron emission tomography (PET) on intended management of patients in the National Oncologic PET Registry (NOPR) for three different diagnostic indications: (a) determining whether a suspicious lesion is cancer (Dx), (b) detecting an unknown primary tumor site when there is confirmed or strongly suspected metastatic disease (cancer of unknown primary origin [CUP]), and (c) detecting a primary tumor site when there is a presumed paraneoplastic syndrome (PNS). METHODS: We reviewed a sample of randomly selected reports of NOPR subjects who underwent PET for Dx and CUP and all reports for PNS to find subjects for analysis. For these studies, we evaluated the impact of PET on referring physicians' intended management, based on their management plans reported before and after PET. RESULTS: Intended management was changed more frequently in the CUP group (43.1%) than in the Dx (23.9%) and PNS (25.4%) groups (CUP vs. Dx, p < .0001; PNS vs. Dx, p < .0001; CUP vs. PNS, p < .0002). Referring physicians reported that, in light of PET results, they were able to avoid further testing in approximately three-fourths of patients (71.8%-74.6%). At the time when the post-PET forms were completed, biopsies of suspicious sites had been performed in 21.2%, 32.4%, and 23.2%, respectively, of Dx, CUP, and PNS cases. CONCLUSION: Our analysis of NOPR data shows that PET appears to have a substantial impact on intended management when used for three common diagnostic indications. IMPLICATIONS FOR PRACTICE: [(18)F]-fluorodeoxyglucose-positron emission tomography appears to have a substantial impact on intended management when used for three targeted diagnostic indications: (a) determining whether a suspicious lesion is cancer, (b) detecting an unknown primary tumor site in a patient with confirmed or strongly suspected metastatic disease, and (c) detecting a primary tumor site in a patient with a presumed paraneoplastic syndrome.
Subject(s)
Fluorodeoxyglucose F18/therapeutic use , Neoplasms/diagnostic imaging , Positron-Emission Tomography , Tomography, X-Ray Computed , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Neoplasms/diagnosis , Neoplasms/epidemiology , Neoplasms, Unknown Primary/diagnosis , Neoplasms, Unknown Primary/diagnostic imaging , Neoplasms, Unknown Primary/pathology , Paraneoplastic Syndromes/diagnosis , Paraneoplastic Syndromes/diagnostic imaging , Paraneoplastic Syndromes/pathology , RegistriesABSTRACT
Neuroendocrine tumors (NETs) account for 8-10% of cases of carcinomas of unknown primary. Most of these cases are poorly differentiated with metastatic disease at the time of diagnosis. However, cutaneous metastatic presentation is rare. We present an interesting case of a 74-year-old woman presenting with cutaneous metastatic involvement from high grade poorly differentiated NET of unknown origin. She was referred to us with a diagnosis of lymphoma. (18)F-fluorodeoxyglucose positron emission tomography/computer assisted tomography imaging at our institution offered a differential diagnosis, including neuroendocrine cancer. Repeat skin lesion biopsy demonstrated "non-Merkel cell" carcinoma, favoring metastatic high-grade neuroendocrine carcinoma.
