Residency Program - Case of the Month

History:

A 38-year-old man was transferred from outside facility for evaluation and management of an intra-abdominal mass.  Pertinent history begins in 2008 when the patient underwent an excision of a skin lesion on his back.  He states that the mass was 1 x 1.5 inches. Pathology showed melanoma (he could not specify the type) and he was told that no further treatment would be required.  The next several years were uneventful until 4 months ago when he began having post-prandial abdominal pain lasting approximately an hour.  In November 2015, the abdominal pain changed and became constant and was not directly related to oral intake or bowel movements. On January 4, 2016, he began experiencing a worsening of his abdominal pain associated with nausea and vomiting with a pertinent history of 35 lb. weight loss. As per patient, he had a CT, US, EGD and colonoscopy.  He states that he was told he had a melanoma recurrence in his abdomen (records do not indicate tissue biopsy) and he was transferred to our facility.

Gross Description:

Received in formalin is a large mass with two attached segments of the bowel (Figure A-B). The ovoid, lobular, firm mass measures 18.2 x 18.4 x 12.6 cm.  Upon opening the small bowel, the tumor is present on the outer surface of the small bowel and invades into the small bowel mucosa.  Upon opening the large bowel, it reveals that the tumor is attached to the large bowel on the outer surface, involves the bowel wall but doesn't seem to grossly invade the mucosa.

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Figure A		Figure B

Histology:

Histologically the tumor cells show atypical groups of cells infiltrating into the small bowel as shown in figures C-D.

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Figure C		Figure D

Lymph nodes are also positive for metastasis (Figure E-F).

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Figure E		Figure F

What is the diagnosis?

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