Metastatic Melanoma

Metastatic melanoma is by far the most common of these tumors to be encountered clinically, and it may be taken as a particular prototype. The hematogenous deposition is usually in the submucosal layer where it may be seen early as small mural nodules, and growth typically results in polypoid masses with a bulky extension

into the lumen. ' ' There is no significant desmo-plastic response. Central ulceration is especially common as the metastasis outgrows its blood supply. In smaller lesions, this may be identified as a "bull's eye" or "target" lesion (Figs. 4-198 and 4-199), in which, characteristically, the borders of the filling defect are well defined and the ulcer is quite large in proportion to the metastatic mass (Fig. 4-200). Linear fissures over the surface of the mass, radiating distinctly to the central collection, produce a "spokewheel" pattern1,235 (Fig. 4201). In the larger lesions, necrosis may be reflected as a large excavating lesion (Fig. 4-202) yielding an ap

Fig. 4-198. Metastatic melanoma to small bowel.

Multiple submucosal nodular masses, some with prominent central ulceration (arrows), are present throughout a length of small intestine. These are described as bull's-eye or target lesions.

(Reproduced from Herlinger and Maglinte.237)

Fig. 4-198. Metastatic melanoma to small bowel.

Multiple submucosal nodular masses, some with prominent central ulceration (arrows), are present throughout a length of small intestine. These are described as bull's-eye or target lesions.

(Reproduced from Herlinger and Maglinte.237)

pearance of aneurysmal dilatation235-240 (Figs. 4-203 through 4-207). Intussusception may be associated with the larger polypoid masses235 (Figs. 4-205 and 4-206).

Dissemination may be single (Fig. 4-208) but is more often multiple. Although metastatic melanomas may involve any portion of the alimentary tract, they tend to be more numerous and more frequent in the small bowel. In an autopsy series of 1,000 cases, secondary small bowel involvement was found in 58%.241 When multiple, they may be either widespread (Fig. 4-209) or confined to a segment of intestine (Figs. 4-198 and 4210). This reflects their mode and periodicity ofvascular distribution.1 Diffuse metastases are infrequently of different sizes (Fig. 4-209), indicating periodic embolic showers. At times, the secondary deposits are present within the field of a specific arterial distribution when, typically, the nodules are of approximately the same size

Melanoma Metastatic

Fig. 4-199. Metastatic melanoma to stomach.

The multiple, centrally ulcerated submucosal lesions are seen en face and tangentially along the curvatures as bull's-eye lesions.

(Reproduced from Meyers and McSweeney.1)

Fig. 4-199. Metastatic melanoma to stomach.

The multiple, centrally ulcerated submucosal lesions are seen en face and tangentially along the curvatures as bull's-eye lesions.

(Reproduced from Meyers and McSweeney.1)

Duodenal Bulb Radiology

Fig. 4-200. Metastatic melanoma to duodenal bulb.

(a) A filling defect with sharply demarcated borders contains a proportionately large ulcer crater. These features are helpful in identifying this lesion as a submucosal nodule with secondary central ulceration, in contrast to a benign peptic ulcer with surrounding edema, the borders of which usually fade away gradually.

(b) Gross specimen demonstrates prominent submucosal mass (arrows) with central ulceration (arrowheads). Pathologically, this type of hematogenous metastasis is described as a "buttercup" lesion. (Reproduced from Meyers and McSweeney.1)

Fig. 4-200. Metastatic melanoma to duodenal bulb.

(a) A filling defect with sharply demarcated borders contains a proportionately large ulcer crater. These features are helpful in identifying this lesion as a submucosal nodule with secondary central ulceration, in contrast to a benign peptic ulcer with surrounding edema, the borders of which usually fade away gradually.

(b) Gross specimen demonstrates prominent submucosal mass (arrows) with central ulceration (arrowheads). Pathologically, this type of hematogenous metastasis is described as a "buttercup" lesion. (Reproduced from Meyers and McSweeney.1)

Melanoma Bowel Metastases Radiology

Fig. 4-201. Metastatic melanoma to stomach.

(a) On the greater curvature, there is a centrally ulcerated submucosal mass. Radiating linear fissure ulcerations result in a distinctive "spokewheel" configuration.

(b) Diagrammatic representation of (a). (Reproduced from Meyers and McSweeney.1)

Fig. 4-201. Metastatic melanoma to stomach.

(a) On the greater curvature, there is a centrally ulcerated submucosal mass. Radiating linear fissure ulcerations result in a distinctive "spokewheel" configuration.

(b) Diagrammatic representation of (a). (Reproduced from Meyers and McSweeney.1)

Fig. 4-202. Metastatic melanoma to small bowel.

A moderate-sized irregular cavity with multiple nodules replaces the lumen of a short segment of ileum. Reflecting its submucosal location, it is non-obstructive in nature. (Reproduced from Gourtsoyiannis and Nolan.80)

Fig. 4-203. Metastatic melanoma to small bowel.

Several bulky polypoid masses involve the mid-small bowel (black arrows). Some have undergone large ulcerations (curved arrows).

(Reproduced from Oddson et al.235)

Fig. 4-203. Metastatic melanoma to small bowel.

Several bulky polypoid masses involve the mid-small bowel (black arrows). Some have undergone large ulcerations (curved arrows).

(Reproduced from Oddson et al.235)

Fig. 4-204. Metastatic melanoma to small bowel.

A large cavitating mass is present in the proximal jejunum

(arrowheads).

(Reproduced from Oddson et al.235)

Fig. 4-204. Metastatic melanoma to small bowel.

A large cavitating mass is present in the proximal jejunum

(arrowheads).

(Reproduced from Oddson et al.235)

Fig. 4-205. Metastatic melanoma to small bowel.

A huge cavitating mass with intussusception is present in the ileum.

(Reproduced from Oddson et al.235)

Fig. 4-205. Metastatic melanoma to small bowel.

A huge cavitating mass with intussusception is present in the ileum.

(Reproduced from Oddson et al.235)

Fig. 4-206. Metastatic melanoma to small bowel.

CT shows a submucosal metastasis (M) is the lead point of an ileal-ileal intussusception in the right lower quadrant.

Fig. 4-206. Metastatic melanoma to small bowel.

CT shows a submucosal metastasis (M) is the lead point of an ileal-ileal intussusception in the right lower quadrant.

Radiation Induced Sarcomas Children

Fig. 4-207. Metastatic melanoma to small bowel.

CT demonstrates aneurysmal dilatation with submucosal masses, a widened lumen, and grossly ulcerated mucosa. Enlarged iliac nodes are also present.

Colon Submucosal Massradiology

Fig. 4-208. Metastatic melanoma to small bowel.

CT demonstrates an ulcerated submucosal mass involving an opacified mid-small bowel loop (arrows).

Fig. 4-208. Metastatic melanoma to small bowel.

CT demonstrates an ulcerated submucosal mass involving an opacified mid-small bowel loop (arrows).

(Figs. 4-210 and 4-211). A further observation that is useful in identifying such submucosal masses at embolic metastases relates to their specific sites on the bowel wall.1,72,73 When the lesion is localized to one wall of the bowel, a distinct predilection is shown for the anti-mesenteric border. In the small intestine, this is readily identified as the convex margin of the loop (Figs. 4-212 through 4-214), since the mesentery supports the concave surface. In the ascending and descending colon, the lateral borders constitute the antimesenteric margins (Fig. 4-211). These findings are apparently related to the entrance of the intestinal vessels on the mesenteric border and their intramural ramifications toward the an-timesenteric side. They are in agreement with Coman's experimental work, which revealed that strictly mechanical and circulatory factors can account for the distribution of some secondary tumors.242

A patient with melanoma with small bowel involvement, a stage III designation, now has available surgical treatment complemented by adjuvant therapy and im-

243-245

munotherapy, with an improved survival rate.

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