Intussusception due to melanoma metastasis

Case contributed by A.Prof Frank Gaillard

Presentation

Abdominal pain, nausea and vomiting.

Patient Data

Age: 50 years
Gender: Male
Modality: CT

Proximal jejunal intussusception over approximately 9cm segment. No significant contrast passage past this point, however bowel loops proximal to the intussusception are not overtly dilated. The stomach is distended with contrast.  No free intraabdominal gas or fluid.

Enlarged left coeliac axis lymph node measures 20mm in short axis. Several bilateral retroperitoneal soft tissue deposits - the largest  nodules are seen adjacent to the left psoas muscle at the level of the renal hilum and in the left paracolic gutter at the level of the iliac crest. Smaller subcentimeter nodules are seen in the pararenal spaces bilaterally. 

Well defined low density right lower pole renal lesion is most likely a simple cyst. The liver, spleen, pancreas , adrenals and kidneys  are otherwise within normal limits.  IDC in situ.

Multiple pulmonary soft tissue masses scattered through both lungs. Expansile lytic left anterior 6th rib lesion.  No further bone lesions identified. Soft tissue deposit in the subcutaneous fat overlying the right iliac crest.

Intussusception is seen as a segment of proximal bowel (blue) and its mesentery (yellow) pulled into a distal segment of bowel (green). At is most distal extend a rounded soft tissue mass is present (red); the lead point. 

Multiple lung metastases (*) and subcutaneous nodules (orange) are noted. 

The patient went on to have a laparotomy and the involved segment of bowel resected. 

Histology

MACROSCOPIC DESCRIPTION:

Small bowel 470mm in length and 30mm in diameter.  The serosal surface is mildly congested.  On the mucosa, three firm, sessile polypoid lesions are identified. The first and third are pale tane. The second nodule has a pigmented brown-black appearance.  The remainder of the mucosa is unremarkable. 

MICROSCOPIC DESCRIPTION:

Sections of the small bowel show three nodules of malignant melanoma. The tumour forms fascicles of spindle cells as well as nests of more epithelioid cells.  The tumour nodules are well-demarcated.  The tumour extends from the mucosa to the subserosa.  It is close to but not breaching the serosa.  The tumour cells have elongated pleomorphic nuclei, conspicuous nucleoli and small amounts of ill-defined pale eosinophilic cytoplasm.  Some of the tumour cells contain brown pigment in the cytoplasm.  Scattered mitoses are seen.  There is no evidence of lymphovascular invasion.  13 lymph nodes are identified with no evidence of metastatic melanoma.  All the nodules are completely excised with clear proximal and distal resection margins. The tumour cells are S-100 and melan-A positive. DOG1 is negative.

FINAL DIAGNOSIS: Jejunal excision: Malignant melanoma x3.

Case Discussion

This case illustrates typical appearances of a small bowel intussusception, which when this long is usually associated with a lead point lesion; in this case a melanoma metastasis. 

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Case Information

rID: 19018
Case created: 2nd Aug 2012
Last edited: 4th Sep 2015
Inclusion in quiz mode: Included

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