Clinical History
A 72-year-old woman presented with nausea, vomiting, and a
25-lb weight loss over a several week period. On physical examination, there was mild epigastric
tenderness to palpation. A CT scan of the abdomen revealed a large mass at the root of the mesentery.
An exploratory laparotomy was performed and several mesenteric biopsies obtained.
Case 4 - Figure 1 - Low power view demonstrating bands of fibrosis dissecting lobules of fat.
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Case 4 - Figure 2 - There is extensive fat necrosis with attendant dense sclerosis. Note that the fibrous areas are paucicellular.
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Case 4 - Figure 3 - Foci of dystrophic calcification are observed in areas of fat necrosis.
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Case 4 - Figure 4 - Clusters of foamy macrophages are scattered throughout the areas of fat necrosis.
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Case 4 - Figure 5 - In some areas, a chronic inflammatory infiltrate is present, consisting primarily of lymphocytes and plasma cells, with occasional eosinophils.
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Case 4 - Figure 6 - The chronic inflammatory infiltrate also includes several lymphoid aggregates.
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Additional Clinical History
Following the biopsy
procedure, the patient was referred to another center for resection of the lesion. A 51 cm segment of
small bowel was resected along with the attached mesentery. The mesentery contained an 8 x 5 x 4 cm,
hard mass that had a yellow to gray cut surface. The mass did not infiltrate the muscularis propria of
the bowel wall.
Histologic Features
Biopsies of the mesenteric mass contained dense fibrosis dissecting lobules of fat. There was
extensive fat necrosis with scattered foci of foamy macrophages. Focal dystrophic calcification was also
present. These features were accompanied by a chronic inflammatory infiltrate composed primarily of
lymphocytes and plasma cells, with lesser numbers of eosinophils. Scattered lymphoid aggregates were
present at the periphery of the mass.
Diagnosis
Sclerosing Mesenteritis
Discussion
Sclerosing mesenteritis (SM) is a rare disease process
involving the small or large bowel mesentery, resulting in the formation of mesenteric masses or diffuse
mesenteric thickening. Histologically, it is characterized by a combination of the following features:
fat necrosis, chronic inflammation, and fibrosis
[1,
2,
3,
4,
5]
. Numerous terms have been applied to this
condition, including retractile mesenteritis [2], mesenteric panniculitis [5], mesenteric lipodystrophy
[3,
4]
, and liposclerotic mesenteritis, just to name a few. Some have held that sclerosing or retractile
mesenteritis, mesenteric panniculitis, and mesenteric lipodystrophy represent distinct entities; however,
the common clinical and histologic features shared by these groups has led others to regard them as a
spectrum of a single entity [1]. For the purpose of this discussion, the three will be considered as a
spectrum of a single entity.
Clinical Features
Sclerosing mesenteritis is a disease of older adults, with a
median age of 60 years
[1,
3]
. Most series have shown a male predominance, with M:F ratios of 2-3:1.
[1,
3,
5]
The most common presenting signs/symptoms are abdominal pain and an abdominal mass. Other
symptoms include weight loss, diarrhea, nausea and vomiting
[1,
3,
5]
. Some patients are asymptomatic but
are found to have an abdominal mass on evaluation for another condition. In those patients with a
significant degree of fibrosis, bowel obstruction may result.
Gross Pathology
Sclerosing mesenteritis most commonly affects the small bowel
mesentery, although it may also involve the mesocolon [5]. The disease most commonly manifests as a
single mesenteric mass or a diffuse thickening of the mesentery, although multiple mesenteric masses may
also occur. The masses are hard and may range from 1-40 cm in greatest dimension, with an average size
of 10 cm in one series [1]. In some cases, the loops of bowel may become adherent and kinked, resulting
in obstruction. On sectioning, the masses are yellow-gray and sometimes gritty
[1,
2]
.
Histologic Features
A combination of fat necrosis, chronic inflammation and fibrosis characterizes
sclerosing mesenteritis. The fat necrosis is typically accompanied by lipid-laden macrophages. In
occasional cases, foamy macrophages are found in the lamina propria of the affected bowel segment, just
above the muscularis mucosae
[1,
2]
. One may also see foci of dystrophic calcification, and a rare case
may contain osteoid [1]. Varying degrees of fibrosis are observed, with fibrous bands infiltrating the
fatty tissue. In those cases that have been classified as mesenteric lipodystrophy in the literature,
there is little to no fibrosis. The inflammatory infiltrate is chronic, composed primarily of
lymphocytes and plasma cells. In many cases, lymphoid aggregates are also present. Importantly, in
sclerosing mesenteritis, there is no infiltration of the disease process into the muscularis propria of
the bowel wall.
Follow-up and Treatment
In most cases, sclerosing mesenteritis follows a self-limited course with no
evidence of disease progression, although development of additional lesions has been reported in a
minority of patients [3]. Regression of the lesion has also been reported [3]. There is no specific
treatment, but some patients require surgical resection when there is accompanying bowel obstruction.
There has been some question regarding a possible association of sclerosing mesenteritis with malignant
lymphoma, owing to the fact that in some series, lymphomas have developed in up to 15% of patients with
sclerosing mesenteritis [3]. Some of the lymphomas have been located in the mesentery or
retroperitoneum, and in these cases, it is possible that the sclerosing mesenteritis represents a
reaction to the lymphoma. In other cases, however, the lymphoma has involved extra-abdominal lymph nodes
in cervical or axillary locations [3].
Differential Diagnosis
The differential diagnosis for sclerosing
mesenteritis includes such entities as inflammatory pseudotumor, mesenteric fibromatosis [6], idiopathic
retroperitoneal fibrosis [7], and sarcomas. Inflammatory pseudotumor has fibrosis in a whorled pattern
and has different clinical findings including fever, elevated erythrocyte sedimentation rate, and anemia.
In contrast to sclerosing mesenteritis, mesenteric fibromatosis infiltrates the muscularis propria of the
bowel wall, lacks a significant inflammatory infiltrate, and is associated with familial adenomatous
polyposis as well as prior abdominal surgery. Idiopathic retroperitoneal fibrosis occurs in a different
location, although the histologic features are very similar. Inflammatory fibrosarcoma of the mesentery
[8] is more cellular than sclerosing mesenteritis and has cytologic atypia. Liposarcoma rarely involves
the mesentery.
References
- Emory TS, Monihan JM, Carr NJ, Sobin LH. Sclerosing mesenteritis, mesenteric panniculitis and mesenteric lipodystrophy: A single entity? Am J Surg Pathol 21:392-398;1997.
- Kelly JK and Hwang WS. Idiopathic retractile (sclerosing) mesenteritis and its differential diagnosis. Am J Surg Pathol 13:513-521; 1989.
- Kipfer RE, Moertel CG, Dahlin DC. Mesenteric lipodystrophy. Ann Int Med 80:582-588;1974.
- Bashir MS and Abbott CR. Mesenteric lipodystrophy. J Clin Pathol 46:872-874;1993.
- Adachi Y, Mori M, Enjoji M, et al. Mesenteric panniculitis of the colon. Review of the literature and report of two cases. Dis Colon Rectum 30:962-966;1987.
- Burke AP, Sobin LH, Shekitka KM, et al. Intra-abdominal fibromatosis. A pathologic analysis of 130 tumors with comparison of clinical subgroups. Am J Surg Pathol 14:33-341;1990.
- Osborne BM, Butler JJ, Bloustein P, et al. Idiopathic retroperitoneal fibrosis (sclerosing retroperitonitis). Hum Pathol 18:735-739;1987.
- Meis JM and Enzinger FM. Inflammatory fibrosarcoma of the mesentery and retroperitoneum. A tumor closely simulating inflammatory pseudotumor. Am J Surg Pathol 15:1146-1156; 1991.
