Ileal intussusception secondary to ileo-cecal-appendiceal metastases of disseminated malignant melanoma

68 years-old male without prior story of cancer presented with 3 days of abdominal pain in right iliac fossa, coluria and vomiting. Blood test demonstrated microcytic hypochromic anemia, coagulopathy and increase of inflammatory markers (C-reactive protein, lactate dehydrogenase and white cell blood count)

CECT showed marked circumferential thickening and heterogeneous enhancement of the wall of distal ilium, cecum, right colon and appendix with ileal intussusception (Figure 1)

No signs of intestinal perforation or obstruction were observed, although minimal fat stranding and fluid and mild wall thickening with submucous oedema of perilesional colon was detected, consistent with colitis (Figure 1).

Nodular lesions in the gallbladder wall consistent with metastases were depicted, but also multiple liver lesions, peritoneal and retroperitoneal adenopathies and multiples implants in gluteus and paravertebral muscles, toracho-lumbar fascia and subcutaneous tissue (Figure 1).

Whole-body PET-CT (Figure 2) showed marked 18F-FDG uptake in the gastrointestinal lesion (SUVmax 10.6) and in the hepatic lesions and mesenteric, muscular and subcutaneous implants visualized in CECT but it also showed supradiaphragmatic dissemination and osseous metastases in left femur and sternum.

Colonoscopy revealed a vegetant mass with inner marginal ulceration and necrosis and histopathological analysis demonstrated a poorly differentiated lesion, positive for S100, SOX-10 and Melan A consistent with metastases of melanoma.

Discussion

Background:

58% of melanoma patients have gastrointestinal metastases at time of death and they represent one third of all small bowel metastases [1-2].

Risk factors for metastases include superficial spreading melanoma, axial primary tumor site, Clark level III or IV, high degree of histologic regression, presence of ulceration, and high mitotic rate.

Gastrointestinal metastases of melanoma without primary cutaneous tumor occur in 26% of cases. Primary intestinal melanoma is extremely rare (<2%)

Clinical Perspective:

Gastrointestinal metastases are mostly asymptomatic. Only 1-5% of cases present with non-specific symptoms such as abdominal pain, gastrointestinal blood loss and weight loss.

There are few cases of intestinal obstruction, intussusception and perforation reported in the literature.

Imaging Perspective:

Metastases of melanoma are mostly localized in the small bowel, with discrepancies in the frequency between jejunum and ilium [1-4]. Other locations include colon, stomach and rectum and extremely rare in esophagus.

The pattern of presentation depends on vascular supply and tumor growth rate [1].

Deposit in the submucosa from a hematogenous spread results in polypoid pattern, the most common, that appears as multiple submucosal nodules with heterogeneous enhancement and central ulceration in large ones [5-6].

Deposit in the submucosa from a lymphatic spread results in an infiltrating pattern with irregular and thickened wall (“apple-core” sign), similar to colorectal adenocarcinoma [6].

Serosal deposit results in a cavitary pattern with circumferential thickening and high risk of necrosis and perforation, or in an exoenteric pattern with fistulous tracts, similar to Chron’s disease [4-6].

10% of melanoma metastases conditioned intussusceptions. Aneurysmal dilatation is extremely rare and differential diagnosis with lymphoma should be made [6].

CECT offers a sensitivity of 66% because it hardly detects little polyps [6].

Atypical metastases in spleen, adrenal glands, kidney, bone, lymph nodes and mesenteric, retroperitoneal, diaphragm and subcutaneous implants characterized melanoma over other malignancies.

Surgical/endoscopic biopsy is mandatory to achieve diagnosis [1].

Outcome:

Surgical resection of gastrointestinal metastasis improves survival rate and palliates the symptoms.

In patients with disseminated melanoma, immunotherapy based on anti-PD1 and anti-CTLA4 antibodies and BRAF/MEK inhibitors offer better progression-free and overall survival compared with chemotherapy [5-6].

In our case, the patient died a few days after the diagnosis before treatment was proposed.

Take-Home Message:

Melanoma metastases should be included in the differential diagnosis of unique or multiple lesions in the small bowel in patients with known melanoma.