Metastatic melanoma causing small bowel intussusception
Persistent vomiting and abdominal pain.
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The proximal small bowel is dilated measuring up to 4 cm, with a transition point in the mid-small bowel. The transition point has the appearance of intussusception, with collapsed bowel distal. No definite mass is identified although at the apex of the intussusception there is the impression of rounded enhancing nodule 2.5cm diameter (best seen on coronal images) which presumably represents the lead point . There is no intraperitoneal free air. There is a small amount of free fluid within the mesentery. Numerous enlarged lymph nodes are present within the mesentery, the largest measuring 1.3 x 0.8 x 1.1 cm. Bilateral large, necrotic / septated cystic adrenal masses are identified. The right is larger than the left measuring 7.4 x 6.5 x 10.7 cm with a solid component inferiorly measuring 3.1 x 1.7 x 2.2 cm. The mass displaces the adjacent liver and kidney. There is some compressive effect on the IVC, although above the mass the IVC fills normally. The left adrenal mass measures 6.4 x 4.1 x 5.1 cm. There is a large hypodense lesion in the right kidney measuring 6.4 x 5.2 cm, with the characteristics of a simple cyst. The left kidney, spleen, pancreas, stomach and colon are unremarkable. No suspicious osseous lesions identified.
Intussusception of the small bowel with possible / probable nodular lead point. Bilateral large adrenal cystic / necrotic masses. Differentials include bilateral pheochromocytomas / adrenal carcinomas or more likely large adrenal metastases. It is likely that these findings all represent the same malignancy although it is unclear which / where the primary is.
CLINICAL NOTES: ??small bowel resection. R adrenal. ? secondary. BIL adrenal masses. Small bowel tumour. Peritoneal nodules.
1. "Right adrenal gland": A disrupted lobulated irregularly shaped piece of tissue weighing 68g and measuring 120x40x30mm. The lesion appears to contain fat and areas of haemorrhage. The lesion has not been inked. Slicing reveals a pale rubbery focally haemorrhagic, focally viscous cut surface with central cystic degeneration. Normal residual adrenal parenchyma is not seen.
2. "Small bowel": A segment of small bowel measuring 100x40mm. The attached mesentery measures 15mm wide. Located 20mm from the nearest resection margin is a polypoid tumour with surface ulceration measuring 40mm in maximum dimension. The surrounding serosa is rugged and has been inked blue. The tumour has a firm cream cut surface and is focally haemorrhagic. It invades through muscularis propria and to the serosa.
A - >>>> (short) and further (long) resection margin
B&C - Composite section B&E - Composite section
F&G - Composite section H&I - Composite section
3. "Peritoneal nodule": Two pieces of cream tissue measuring 10 and 15mm each.
1. Sections show adrenal gland which has been replaced by tumour. The tumour consists of sheets of tumour cells which have large cells. The cells in areas have large irregular folded nuclei and in some areas show prominent nuclear grooves and small nucleoli. There is a moderate amount of eosinophilic cytoplasm seen. In some areas the cells have a slightly epithelioid nature in the cytoplasm but in other areas are spindled.
2. Sections show small bowel which has a tumour located within the bowel wall which ulcerates through the mucosa. The tumour consists of sheets of tumour cells which have a similar morphology to specimen 1. Tumour invades through the full thickness of the bowel wall. No angiolymphatic involvement is seen. Up to 13 mitosis per 10 hpf are present. No necrosis is seen. Tumour extends into the muscularis propria but does not appear to penetrate through the serosa. Immunohistochemistry shows tumour cells are positive with S-100, mlan-A and HMB-45. Focal positive with CD117. Negative in Cam5.2, CD20, CD45, Desmin, AE1/AE3, CD34, calretinin, CD3, CD30 and DOG-1.
3. Sections show multiple fragments of reactive peritoneal tissue which has a focal papillary architecture. The papillary cores are lined by bland mesothelial cells and underlying thickened fibrous connective tissue. No evidence of malignancy is seen.
1. Right adrenal gland: Malignant Melanoma
2. Small bowel: Malignant melanoma 30mm in maximum dimension. Tumour appears to be confined to muscularis propria. No angiolymphatic involvement.
3. Peritoneal nodule: Benign mesothelial hyperplasia.
The histological and immunohistochemical features favour a malignant melanoma. A cutaneous primary should be sought.
Short segment small bowel intussusception often has no pathological lead point, however long segment intussusception should prompt a careful look for a mucosal lesion or other abnormality. Melanoma is known to metastasize to intestinal mucosa.
Benign adrenal lesions are much more common than malignant, in particular adenomas, even in a patient with a known primary. However, given the large size and heterogeneity of the adrenal masses in this case, metastasis has to be favored over benign lesions.