Metastatic melanoma - small bowel

Case contributed by Dr Bruno Di Muzio

Presentation

Previous history of cutaneous melanoma.

Patient Data

Age: 80 years
Gender: Male
Nuclear medicine

PET-CT (18F-FDG)

Marked radiotracer uptake within the proximal jejunum concerning for metastatic deposit, no other suspicious lesions identified. 

CT

CT Abdomen and pelvis

Focal hypodense mass within a proximal jejunum segment correlating with the findings on PET. The remainder of the study is unremarkable. 

The patient underwent surgical resection and the lesion was confirmed to represent a melanoma metastatic deposit. There are literature reports showing that up to 60% of patients with melanoma will have gastrointestinal metastasis at autopsy, but only less than 5% of them will have these metastases diagnosed 1

Microscopy: The sections taken through the lesion, show a large nodule, situated predominantly in the submucosa, composed of large polygonal cells with prominent nuclei are prominent and clear light with patchy brown pigment. Focally, the surface is ulcerated and no mucosa is seen. The nests of cells pushing into underlying muscularis propria and focally into superficial subserosa. The lesion appears to be completely excised in the proximal distal planes of section.

Macroscopy: "Proximal jejunum".  An unoriented segment of bowel 35 x 30 mm (length x width) bearing minimal attached mesentery, up to 3 mm.  There is haemorrhage over the serosal surface.  Centrally,  the mucosa bears a ulcerated brown-black lesion with well demarcated, rolled up edges and central necrosis, 25 x 20 x 18mm. The lesion is 3 mm from the blue inked margin (+3 mm of amputated part) and 15 mm from the black inked margin (+3 mm of amputated part).  The lesion abuts the serosal surface (inked green).  The remaining mucosa appears normal.  Part processed.

Conclusion: Proximal jejunum metastatic melanoma, completely excised.

Case Discussion

This case illustrates what likely represents melanoma metastatic disease to the small bowel, which is not that uncommon. This patient has had previous imaging follow-ups that were clear for metastatic lesions. This is a presumed diagnosis based on the imaging features and clinical context. 

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Case information

rID: 61575
Published: 9th Jul 2018
Last edited: 16th Aug 2018
Inclusion in quiz mode: Excluded

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