Case of the Month - July 2017

This case can be downloaded and read as an PDF or read on this page below.

Click here to view the PET and CT images for this case through an interactive website provided by Hermes Medical Solutions.

Clinical History

47-year-old female with a previous history of melanoma of the right leg in 2002. Represented following acute small bowel obstruction secondary to an intussusception due to histologically proven metastatic melanoma. Staging PET-CT requested to assess extent of disease prior to further treatment.

Findings

An FDG scan was acquired from skull base to below knees together with a low dose CT scan for attenuation correction and image fusion.

Two foci of intense tracer uptake are seen in the right upper quadrant inferior to the liver. On the CT component of the study these correlate with two soft tissue masses within the gallbladder, one in the body and the other in the gallbladder neck. There are also two discrete foci of increased tracer uptake seen associated with subcutaneous nodules, measuring 9mm and 14mm respectively, just above the medial aspect of the right knee. Tracer distribution is otherwise physiologic.

Note is made of a 6mm non-FDG avid nodule in the left anterior chest wall, several small gallbladder calculi, and a small bowel anastomosis. No further significant CT findings are identified.

Interpretation

The scan findings are in keeping with two in-transit metastases and two gallbladder metastases.

Comment: Whilst the differential diagnosis for the gallbladder appearances includes cholecystitis, the patient was clinically asymptomatic at the time of the scan.

Follow-up

The patient subsequently underwent a segment IV and V liver resection with en block cholecystectomy and resection of the two subcutaneous nodules from the right leg. Histology of the polypoid gallbladder lesions and nodules confirmed metastatic melanoma.

Key Teaching points and Discussion

References

Das Gupta T, Brasfield R. Metastatic melanoma: a clinicopathological study. Cancer 1964; 17:1323-39.

Dong XD, Dematos P, Prieto VG, Siegler HF. Melanoma of the gallbladder: a review of cases seen at Duke University Medical Center. Cancer 1999;85(1):32-39.

Rehani B, Strohmeyer P, Jacobs M, Mantil J. Gallbladder metastasis from malignant melanoma: diagnosis with FDG PET-CT. Clin Nucl Med. 2006;31(12):812-3.

Ozülker T, Ozülker F, Cicin I, Ozpaçac T. A case of malignant melanoma with cardiac and gallbladder metastases detected by FDG PET-CT. Clin Nucl Med. 2009;34(12):948-9.

Evidence-based Indications for the use of PET-CT in the United Kingdom 2012 - Skin Tumours

Published by the RCP London, Glasgow, Edinburgh, RCR, BNMS, and NICAG

http://www.rcplondon.ac.uk/resources/evidence-based-indications-use-pet-ct-uk-2012