Gossypiboma-induced abdominal fibrosarcoma in a German shepherd

A 5-year-old 82.3-lb (37.3-kg) spayed German shepherd was presented to a referral center for evaluation of lethargy, constipation, tenesmus, dysuria, and inappetence. The dog had ingested rib bone and cartilage within five days of presentation. It also had reportedly had a subjectively distended abdomen since a cesarean section and ovariohysterectomy were performed two years prior to presentation.

Initial findings

At presentation, the patient was bright, alert, and responsive and had an elevated body temperature of 102.8 F (39.3 C). The dog's heart rate was 168 beats/min, its mucous membranes were tacky, and it was estimated that the dog was 5% to 7% dehydrated. The dog's abdomen was tense and distended. No other significant findings were identified during the physical examination.

A serum chemistry profile revealed hyperglobulinemia, hyperphosphatemia, hyponatremia, hyperkalemia, and decreased lipase activity. A complete blood count revealed neutrophilia, monocytosis, and leukocytosis (Table 1).

Table 1: Abnormal laboratory results

Parameter

Patient's values

Reference range

Serum chemistry profile

Globulin (g/dl)

3.7

1.6–3.6

Phosphorus (mg/dl)

6.3

2.5–6

Sodium (mEq/L)

136

139–154

Potassium (mEq/L)

5.7

3.6–5.5

Lipase (IU/L)

53

77–695

Complete blood count

Neutrophils (/µl)

17,091

2,060–10,600

Monocytes (/µl)

2,743

0–840

Leukocytes (/µl)

21,100

4,000–15,500

Two-view abdominal radiography demonstrated decreased serosal detail (Figures 1 & 2). An approximately 18-x-17-x-14-cm soft tissue opacity was visualized in the right cranioventral abdomen, displacing the stomach in a craniodorsal direction and the intestines caudally. An approximately 8-x-1-cm folded, linear, mineral-opaque foreign structure was in close association with and possibly within the abnormal-appearing opacity.

Figure 1: A right lateral abdominal radiograph revealing a round soft tissue opacity (edges marked by black arrows) and a linear mineral-opaque object in the cranial abdomen (white arrow).

Figure 2: A ventrodorsal abdominal radiograph revealing a round soft tissue opacity (edges marked by black arrows) and a linear mineral-opaque object in the cranial abdomen (white arrow).

Relevant findings from an abdominal ultrasonographic examination included a large volume of flocculent ascites and an approximately 12-cm-wide cystic structure that contained additional flocculent fluid and material with a hyperechoic appearance (Figure 3). A sample of the ascites was collected via abdominocentesis for evaluation in-house by the veterinarian. This fluid had a serosanguineous appearance with a total protein concentration of 3 g/dl, a specific gravity of 1.025, a packed cell volume of 5%, and a glucose concentration of 132 mg/dl. Microscopic evaluation revealed red blood cells and nondegenerate neutrophils. No intracellular or extracellular bacteria were seen. Aerobic culture of the abdominal fluid was negative for growth after 72 hours.

Although not performed in this case, further evaluation of the ascites by a pathologist can yield critical diagnostic information. Specifically, a differential cell count is required to classify the effusion into a transudate or exudate. Additionally, a more through microscopic evaluation or sedimentation examination may have resulted in information regarding the flocculent material noted during the ultrasound.

Figure 3: An ultrasonogram revealing a large fluid-filled cyst and hyperechoic shadow. The edges of the cyst are marked by red arrows, and the shadowing representing the foreign material is marked by a white arrow.

Differential diagnoses

The main differential diagnosis at this time was cystic encapsulation of foreign material located outside of the gastrointestinal tract. Potential causes included gossypiboma, penetrating injury, or migration of ingested foreign material.

Exploratory laparotomy

An abdominal exploratory surgery was performed. Numerous fibrous adhesions were found throughout the entire abdomen. The cystic structure had a firm capsule that adhered to the stomach, spleen, intestines, and peritoneum. The small intestines were adhered together and were sequestered to the caudal abdomen. The intestinal serosa was bright red, and fibrous adhesions covered all serosal surfaces. No intestinal motility was noted. 

The small intestinal adhesions were dissected by using a combination of bipolar electrocautery and digital manipulation. The abnormal tissue was removed en masse and saved for histologic examination. A Jackson-Pratt drain was placed in the abdomen and secured with 3-0 Prolene (Ethicon) suture in a Chinese finger-trap pattern. The abdomen was lavaged and drained before closure. Anesthesia and recovery were uneventful.

Postoperative care

A 75-μg fentanyl patch (2 μg/kg cutaneously) was placed for continuous analgesia. Postoperative care included administering a balanced hypotonic crystalloid fluid (150 ml/hr intravenously), hydromorphone (0.1 mg/kg intravenously q.i.d. as needed for pain), cefazolin (22.7 mg/kg intravenously t.i.d.), and tramadol (4 mg/kg orally b.i.d.).

The Jackson-Pratt drain was maintained for an additional two days and was emptied every two to four hours during that time. The fluid volume collected ranged from 640 to 750 ml (17 to 20 ml/kg) per 24-hour period.

The drain was removed three days after surgery. The patient's vital signs were normal at that time, and the dog was discharged to its owners later that day.

Second presentation

Thirteen days after the surgery, the patient was presented to the referral center for evaluation of weakness, persistent vomiting, and anorexia. The admitting physician assessed the patient to be hypovolemic. The dog exhibited pain upon palpation of the abdomen.

Hospitalization and diagnostic testing to determine the cause of the vomiting and supportive care to control the clinical signs were recommended and declined. The owners said that they had previously discussed euthanasia because of the dog's deterioration and would request that service from the referring veterinarian. However, the patient died at home the day after her last evaluation at our referral center.

Histologic examination

The abdominal cyst was fixed in 10% neutral buffered formalin and submitted to the University of Arizona Veterinary Diagnostic Laboratory for examination. Gross examination revealed a fibrous-connective-tissue-encapsulated cystic mass containing a largely intact cotton gauze foreign body and green metal radiographic marker strip surrounded by fibrinohemorrhagic exudate, consistent with a gossypiboma (Figures 4A & 4B).1

Figure 4A: The opened cystic mass after partial fixation in formalin. Note the irregular fibrous connective tissue capsule, cystic cavity, and fibrinohemorrhagic exudate with embedded cotton gauze foreign matter along the inner aspect of the capsule.

Figure 4B: The contents of the cystic mass after partial fixation in formalin. Note the largely intact cotton gauze foreign body and green metal marker strip (arrow), consistent with a retained laparotomy towel.Sections of the cyst capsule and its contents were prepared and processed routinely and stained with hematoxylin and eosin for histologic examination. Histologically, the cyst capsule was composed principally of organizing fibrous connective tissue containing multifocal lymphocytic aggregates and areas of mineralization. Numerous longitudinal and cross-sectional profiles of clear refractile fibrillar foreign material were embedded in the inner aspect of the capsule and present in the lumen. Individual fibers contained a hollow core and had collective morphologic features consistent with cotton fibers. Cotton fibers were surrounded by amorphous eosinophilic matrix and cellular debris within the lumen (Figure 5A) and by numerous macrophages within the inner aspect of the capsule (Figure 5B).   

Figure 5A: A photomicrograph of the foreign body matter in the cystic lumen. Note the multiple longitudinal and cross-sectional profiles of clear refractile fibers (arrow) surrounded by amorphous eosinophilic matrix and cellular debris. The hollow core of individual fibers and other morphologic features is consistent with cotton (hematoxylin-eosin stain; bar = 50 μm). Figure 5B: A photomicrograph of the inner aspect of the cyst capsule. Note the cotton fibers (arrow) surrounded by macrophages, accompanied by fibroplasia and hemorrhage (hematoxylin-eosin stain; bar = 50 µm).

Multifocally, within the capsule, there was an infiltrative population of moderately pleomorphic polygonal-to-spindle-shaped neoplastic cells arranged in bundles, transitioning from areas of fibroplasia (Figures 6A & 6B).

Neoplastic cells contained large ovoid-to-spindle-shaped nuclei with prominent nucleoli and were invested within eosinophilic stroma with indistinct cytoplasmic borders. There was an average of five mitotic figures per 10 400X-magnification fields. Multiple extracapsular venules contained emboli composed of neoplastic cells similar to those in the wall but having greater pleomorphism and higher mitotic activity (Figures 6C & 6D).

Immunohistochemistry revealed that neoplastic cells in both the capsule and venules were strongly positive for vimentin expression and negative for smooth muscle actin expression, consistent with a fibrosarcoma.

Figure 6A: A photomicrograph of a fibrosarcoma arising in the cyst capsule and invading venules. Note the infiltrative population of neoplastic cells arranged in bundles, transitioning from areas of fibroplasia within the cyst capsule. Arrows indicate the interface between fibroplasia and neoplasia (hematoxylin-eosin stain; bar = 200 µm).

Figure 6B: A photomicrograph of higher magnification of the neoplastic tissue noted in Figure 6A. Note the polygonal-to-spindle-shaped neoplastic cells containing large ovoid-to-spindle-shaped nuclei with prominent nucleoli and indistinct cytoplasmic borders invested within eosinophilic stroma. Also note the mitotic figure (arrow) (hematoxylin-eosin stain; bar = 50 µm).

Figure 6C: A photomicrograph of a representative tumor embolus in an extracapsular venule (hematoxylin-eosin stain; bar = 200 µm).

Figure 6D: A photomicrograph of higher magnification of the tumor embolus depicted in Figure 6C. Note the high mitotic rate and pleomorphism. Also note the mitotic figures (arrows) (hematoxylin-eosin stain; bar = 50 µm).

Discussion

The term gossypiboma is derived from the Latin gossypium, meaning cotton, and the suffix -oma, meaning growth. It is a general term used to refer to surgical equipment or textiles accidentally left in a body cavity after surgery. Reports of granulomas and malignant tumors induced from surgically derived foreign material are infrequently reported in the veterinary and human medical literature.

Reported cases

To our knowledge, this case report is only the second report involving the development of an intra-abdominal fibrosarcoma associated with a sponge gossypiboma in a dog.2 Case reports regarding malignant tumors in the human medical field include the development of angiosarcoma3,4 and numerous other sarcoma types.4 Veterinary reports include the development of an extraskeletal osteosarcoma in a dog5 and fibrosarcoma development in a cat6 and in a mouse model.7

An accurate frequency of occurrence of gossypiboma is impossible to determine given the lack of standardized reporting mandates and asymptomatic nature of most veterinary cases. Induction of a malignant tumor by a gossypiboma is likely to represent only a small percentage of this population.

In veterinary reports, foreign bodies have been inadvertently left behind during cranial cruciate ligament repair,5 ovariohysterectomy (elective or pyometra),2,6,8-11 laparotomy (retained testicle or intestinal biopsy),11 and wound repair11 but frequently did not induce a malignancy. Although several case reports involved fabric-derived foreign material inadvertently left at the time of surgery, other foreign bodies frequently reported are metal and are the result of traumatic events (bullet, shrapnel, wire) or medical implants.4

Models to determine the carcinogenic properties of surgically implanted sterile foreign material have been developed in animals.7,12 The surface of the implanted foreign material is soon covered with plasma proteins and surrounded by neutrophils, lymphocytes, and monocytes. The monocytes differentiate into macrophages and form multinucleated giant cells, making up most of the cells surrounding the foreign material.12 Eventually a fibrous connective tissue capsule forms around the foreign material to create a microenvironment for the proliferation of abnormal mesenchymal stem cells, making this microenvironment possibly the most important determinant of transformation into a neoplastic process.3,4 The generation of free radicals3 and mutation of normal cells appear to play a role in the perpetuation of chronic inflammation and the eventual development of tumors and is described in detail elsewhere.12-14

Clinical signs of gossypiboma

Patients may not become symptomatic for weeks to years, and discovery is often incidental.6,8,11,15,16 In symptomatic cases, reported clinical signs have included vomiting and diarrhea11; depression, weight loss, and anorexia10; infection, abdominal cramping, and small bowel obstruction16; and hematuria and pain.8 Physical examination findings have included swelling, a palpable abdominal or subcutaneous mass, and draining sinus tracts.5,9,11,15

Imaging

A gossypiboma can be discovered and confirmed by using a combination of imaging modalities including radiography,5,11 ultrasonography,10,11,17 fistulography,9 computed tomography,17 and magnetic resonance imaging.18

Radiographic findings can be unremarkable if a gauze foreign body does not contain radiopaque material similar to what was seen in this case.9 The most frequent radiographic finding in a case series of eight dogs with retained surgical sponges was a localized gas lucency that appeared either speckled or in a whirl-like configuration.11 In another case study, the gauze foreign body was diagnosed when radiopaque monofilaments within the surgical sponge were observed during survey radiography of the affected limb.12

If survey radiographs are nondiagnostic, then an ultrasonographic examination of the affected area or abdomen can be performed. Reports of the ultrasonographic appearance of a foreign body have varied and include an ill-defined mass with acoustic shadowing,9 a hyperechoic mass,15 a mass with a hypoechoic outer layer and a hyperechoic inner layer with acoustic shadowing seen deep to the mass (for an encapsulated mass),10 and a hypoechoic mass with an irregular hyperechoic center.11 The findings in this report included echogenicities that were consistent with encapsulated, hyperechoic abnormal material and fluid. Masses may be associated with granulomas, abscesses, calcification, or gas pockets, and the acoustic shadowing for each will differ.10

Treatment and prevention

Surgery is the treatment of choice to remove any foreign material and any abnormal tissue with which it is associated. Adhesions found throughout the abdomen complicated the complete removal of all abnormal tissue in this case. The severity of the adhesions found in this case is not uncommon and has been reported in other cases involving the bladder and small intestines8 and the jejunum, colon, arteries, kidney, and ureter.18

The aggressive nature of the foreign body-associated tumor described in this case report underscores the importance of appropriate surgical technique, including accurate preoperative and postoperative sponge counts. Risk factors associated with a gossypiboma in people include an unplanned procedure, distractions in the operating gallery, poor communication between the technical staff and surgeons, staff changes, patient obesity, and surgeries performed on an emergency basis.16 Although veterinary studies to evaluate specific risk factors are lacking, these events should be considered risk factors in veterinary patients as well.

Standardized processes for communication and for accounting for all instruments, laparotomy towels, and gauze and an established protocol to further investigate missing materials are simple strategies that can prevent this surgical complication. Furthermore, the use of radiopaque markers embedded within laparotomy towels and gauze can facilitate the rapid discovery of a retained surgical foreign body by using survey radiography.

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