Patrick Guinan, Clinical Associate Professor of Urology, Department of Urology, University of Illinois College of Medicine, Chicago, IL; Pauline Chou, Professor of Pathology, Department of Pathology, Northwestern University School of Medicine, Chicago, IL
Patrick Guinan, MD
Clinical Associate Professor of Urology Department of Urology University of Illinois College of Medicine Chicago, IL
Pauline Chou, MD
Professor of Pathology Department of Pathology Northwestern University School of Medicine Chicago, IL
Desmoid soft tissue tumors are rare. The authors reviewed the literature and found 648 reported cases. Of these cases, only two presented as an abscess and none as gram-negative sepsis. The au?thors report the first case of a desmoid tumor presenting as septicemia ( and ) and an abscess. This case highlights the challenges in diagnosing this rare pathological entity.
Desmoid is derived from the Greek word desmos, meaning band or tendon.1 The medical meaning of desmoid is a rare type of soft tissue tumor. Soft tissue tumors are derived from mesoderm and originate in nonepithelial extraskeletal tissue. Soft tissue tumors are uncommon; only 9,420 cases were estimated to occur in 2005.2 Ac?cording to Weiss and Goldblum, there are 14 major subdivisions of soft tissue tumors, one of which includes fibromatoses.3
Fibromatoses are benign fibrous tissue proliferations characterized by (1) proliferation of well-differentiated fibroblasts; (2) an infiltrative pattern of growth; (3) the presence of collagen; and (4) the lack of mitotic activity. Weiss and Gold?blum caution that "the term fibromatosis should not be applied to nonspecific fibrous proliferations that are part of an inflammatory process."3 Fibromatoses are di?vided into superficial and deep tumors (Table 1). The deep fibromatoses, also referred to as des?moid tumors,4 can be intra-ab?dominal or extra-abdominal. Intra-ab?do?minal desmoids can be pelvic or me?senteric. A review of the literature re???vealed most cases (80%) were extra-abdominal; the remaining 20% were intra-abdominal, whether pelvic or mesenteric. Fewer than 10% of all des?moids are of the mesenteric variety.
Desmoid tumors have been described as being "quite rare"5 and "extremely rare."6 They usually present as painless, slowly enlarging masses. These tumors are usually benign but can infiltrate contiguous structures.7 Desmoids can also recur, particularly those associated with Gardner's syndrome; however, with wide excision, the recurrence rate is low.
Because of their rarity and protean manifestations, desmoid tumors present a diagnostic challenge and are seldom diagnosed preoperatively. We present a case of presumed mesenteric fibromatosis that exemplifies this dilemma.
A previously healthy 67-year-old white man awoke at 5: 00 am with violent shaking chills and fever. His only significant medical history was a bleeding duodenal ulcer 5 years earlier. He had experienced no recent fevers or abdominal pain. The patient was taken to the emergency de?partment where sepsis, initially attributed to pneumonia, was diagnosed. The gram-negative (Pseudomonas and Candida) sepsis was treated and controlled emergently with antibiotics and fluids.
A contrast-enhanced computed tomo?g?raphy (CT) scan performed 3 days after admission to the hospital revealed a large, complex, heterogenous, left ab?dominal mass measuring 10 x 12 cm and extending into the pelvis (Figure 1). The mass was contiguous su?periorly with the transverse colon and ileum and was contiguous inferiorly with the urinary bladder and sigmoid colon, which contained multiple diverticula. The mass contained enhancing soft tissue components, gas, fluid, and contrast.
The workup continued with colono?s?copy, which was negative for familial adenomatous polyposis (FAP), but re?vealed diverticular disease. Five days after ad?mission, while the workup continued, the mass spontaneously ruptured. This re?sulted in acute abdomen, which required an emergency exploratory la?parotomy.
The laparotomy revealed a pus-filled left lower quadrant, which contained an opened 10- to 12-cm abscess cavity that adhered to the ileum and sigmoid colon. The abscess cavity contained a 5- to 7-cm solid mass (Figure 2). Because of the possibility of malignancy, the entire abscess cavity and mass were widely resected and a Hartmann's pouch and di?verting ileostomy were created. The patient's postoperative recovery was un?eventful except for an episode of me?t?abolic acidosis, which required rehospitalization. The Hartmann's diversion and ileostomy were closed 4 months later.
The pathologist's report confirmed the gross surgical findings. The microscopic examination revealed sheets of spindle cells interspersed with inflammatory cells and few (if any) mitotic figures (Figure 3). Higher-power magnifications revealed an inflammatory infiltrate (Figure 4). Immunohistochemical stains were negative for c-Kit, ruling out a gastrointestinal stromal tumor. The final pathology diagnosed the lesion as mesenteric fibromatosis. A separately resected liver nodule was negative for malignancy.
Desmoid tumors are deep fibroma?toses, and mesenteric desmoids are the least common variety (Table 1). A review of the literature revealed approximately 648 cases of desmoid tumors, of which 115 (23%) were mesenteric (Table 2).1,5,8-14
A unique feature of desmoid tumors is their association with Gardner's syndrome or FAP. There is an autosomal dominant genetic component to FAP. The incidence of desmoid tumors among patients with this condition has been reported to be 852 times higher14 than that of the general population. Desmoids associated with FAP are more common because there are often multiple tumors and the tumors tend to recur. Colonoscopy ruled out FAP in our patient.
The differential diagnosis in this case, given the presentation and CT findings, included diverticulitis with abscess, adenocarcinoma of the colon, lymphoma, gastrointestinal stromal tumor, urachal remnant, and a small bowel lymphoma. Mesenteric fibromatosis would have been a statistically remote consideration.
Our case was unusual for several reasons. First, desmoid tumors are rare. The annual incidence is estimated to be be?tween two and five cases per million.8 Second, our patient's presentation was unusual, because he had neither pain nor a mass but had an abscess and gram-negative sepsis. Abscesses are uncommon, and the literature contained no previously re?ported cases presenting as gram-negative sepsis. Unlike our case, most patients present with a gradually enlarging ab?dominal mass that becomes clinically relevant only when it encroaches on contiguous vital structures such as the bowel, nerves, or major vessels. There were four cases of desmoid tumors presenting as fever, but no further clinical details were given to explain the fevers.9,12 A preoperative diagnosis of desmoid tumor is unusual unless a diagnosis of FAP has been made previously. Third, desmoids are not usually associated with inflammatory processes or abscesses.
The most interesting finding in this case of mesenteric fibromatosis was the presence of inflammatory cells and an abscess. Weiss and Goldblum specifically state that "the term fibromatosis should not be applied to nonspecific reactive fibrous proliferations that are part of an inflammatory process."3 Burke and colleagues also note that "lack of inflammation within the tumor is a key feature of fibromatosis."12 Our patient's 10 x 12-cm lesion was predominantly a fibroproliferative process with an associated abscess cavity. Although abscesses have been previously reported with desmoid tumors, these cases have not been described in detail. In this case, while the radiologist found numerous diverticula in the sigmoid colon, the pathologist noted no communication between the diverticula and the abscess. Based on these findings, a diagnosis of mesenteric fibromatosis was made, which was confirmed by a second opinion from the Armed Forces Institute of Pathology.
Our case is unusual because the clinical presentation did not conform to that expected of a desmoid tumor. Our patient did not present with a slowly enlarging painless mass, but instead had sudden onset of fever. The gross surgical and pathology findings also showed a large inflammatory process and Pseudomonas gram-negative sepsis, which has not been reported before this case. According to Weiss and Goldblum, these findings are grounds for excluding the diagnosis of fibromatosis; however, our case indicates that an inflammatory process should not necessarily rule out the possibility of a desmoid tumor. The pathologists, including those at the Armed Forces Institute of Pathology who gave a second opinion, agreed that this was a case of mesenteric desmoid tumor. This report suggests that appearances can be deceiving when it comes to diagnosing desmoid tumors.
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