BackgroundFDG-PET/CT imaging has an emerging role in staging and treatment planning of various tumor locations and a number of literature studies show that also the carcinoma of the anal canal may benefit from this diagnostic approach. We analyzed the potential impact of FDG-PET/CT in stage definition and target volume delineation of patients affected by carcinoma of the anal canal and candidates for curative radiotherapy.MethodsTwenty seven patients with biopsy proven anal carcinoma were enrolled. Pathology was squamous cell carcinoma in 20 cases, cloacogenic carcinoma in 3, adenocarcinoma in 2, and basal cell carcinoma in 2. Simulation was performed by PET/CT imaging with patient in treatment position. Gross Tumor Volume (GTV) and Clinical Target Volume (CTV) were drawn on CT and on PET/CT fused images. PET-GTV and PET-CTV were respectively compared to CT-GTV and CT-CTV by Wilcoxon rank test for paired data.ResultsPET/CT fused images led to change the stage in 5/27 cases (18.5%): 3 cases from N0 to N2 and 2 from M0 to M1 leading to change the treatment intent from curative to palliative in a case.Based on PET/CT imaging, GTV and CTV contours changed in 15/27 (55.6%) and in 10/27 cases (37.0%) respectively. PET-GTV and PET-CTV resulted significantly smaller than CT-GTV (p = 1.2 × 10-4) and CT-CTV (p = 2.9 × 10-4). PET/CT-GTV and PET/CT-CTV, that were used for clinical purposes, were significantly greater than CT-GTV (p = 6 × 10-5) and CT-CTV (p = 6 × 10-5).ConclusionsFDG-PET/CT has a potential relevant impact in staging and target volume delineation of the carcinoma of the anal canal. Clinical stage variation occurred in 18.5% of cases with change of treatment intent in 3.7%. The GTV and the CTV changed in shape and in size based on PET/CT imaging.

Our data suggest that pre-treatment FDG-PET/CT SUVmax cannot directly predict tumor response and survival, but it is strongly associated with tumor characteristics such as primary tumor stage and histology, being the first one of the most important and validated prognostic factors for anal cancer.

Malignant paraganglioma of the glomus vagale is a rare tumor entity originating from paraganglia or glomus cells. It typically affects middle age. It differs from benign paraganglioma because of its rapid growth and more aggressive clinical behavior. We report the case of a 40-year-old man presenting with a 5 cm lesion in the upper right cervical region detected by computed tomography (CT) and magnetic resonance imaging (MRI), which also showed enlargement of ipsilateral spinal and jugulodigastric lymph nodes with contrast enhancement. Clinical manifestations at diagnosis included a partial neurological deficit involving the right cranial nerves X, XI and XII. Tumor vascularization was assessed by digital angiography. The tumor mass was entirely removed by a right cervical approach with en-bloc resection with the regional lymph nodes. Histopathological examination showed a paraganglioma with cellular pleomorphism, necrotic microfoci, perineural infiltration and angiogenesis. Massive metastases in two of three jugulodigastric and one spinal lymph nodes on the right side were also detected. Postoperative workup included MRI, positron emission tomography (PET)/CT, meta-iodine-benzyl-guanidine (MIBG) scan, liver ultrasound and chest radiography. Subsequently, the patient underwent conformal radiotherapy with concomitant cisplatin administration. At the last clinical and radiological follow-up examination 5 years after completion of treatment, the patient was free of tumor recurrence. The integrated treatment by surgery and chemoradiation was feasible and effective in the management of this rare case of malignant paraganglioma of the glomus vagale. Multicenter studies should be done to increase the knowledge of tumor presentation and natural history and to analyze the possible treatment options.

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