History
A 7-year-old 30-kg (66-lb) castrated male Belgian Malinois was examined by a veterinarian because of sudden-onset left pelvic limb lameness. The veterinarian suspected a cranial cruciate ligament rupture, and the dog was referred to a veterinary teaching hospital for further evaluation. Two years earlier, the dog underwent castration to remove a left testicular Sertoli cell tumor as well as drainage and omentalization of several prostatic abscesses.
Clinical and Clinicopathologic Findings
On physical examination, the dog was bright, alert, and responsive. No neurologic deficits were evident. A firm mass in the caudal portion of the abdomen was detected, palpation of which elicited no signs of pain. Signs of pain were associated with extension of the left stifle joint and both hip joints and on palpation of the distal aspect of the left femur. A firm, bony swelling was palpated in the distal region of the left femur; radiography revealed a proliferative and expansile lytic lesion with loss of corticomedullary definition of the metaphysis. Thoracic radiographic findings were unremarkable. Abdominal ultrasonography revealed a hypoechoic, shadowing mass in the right caudal portion of the abdomen as well as a mass with occasional cystic regions and a single shadowing area (suspected to be mineralization) in the area of the prostate. Ultrasound-guided fine-needle aspirate specimens of the prostate, femur, and caudal abdominal mass were submitted for cytologic examination. Cytologically, findings for the prostatic aspirate specimen were nondiagnostic, and collection of another sample was recommended; findings for the femoral aspirate specimen were consistent with a diagnosis of sarcoma. The aspirate specimen of the caudal abdominal mass was moderately cellular and markedly hemodiluted (Figure 1). There were moderate numbers of vacuolated macrophages, many of which were multinucleated (≤ 5 nuclei). Macrophages commonly contained basophilic, cylindrical material that ranged in size from 2 to 10 μm × 7 to 30 μm, often with a tapered end. Occasionally, strands of material ≥ 200 μm in length with a uniform width of approximately 10 to 12 μm were observed. Extracellular aggregates of the same material were observed frequently and were often associated with cellular debris. There were also low numbers of refractile rhomboidal yellow to orange crystals in macrophages, consistent with hematoidin.
Photomicrographs of a fine-needle aspirate specimen from a mass in the right caudal portion of the abdomen of a dog that was undergoing evaluation because of sudden-onset left pelvic limb lameness. Palpation of the abdominal mass elicited no signs of pain. A—The sample is hemodiluted with aggregates of ruptured cells and extracellular debris and few intact vacuolated macrophages and multinucleated giant cells. Debris is variably sized, basophilic, cylindrical material, often with a tapered end, which is sometimes seen within macrophages (arrow). Higher-magnification views of 2 macrophages are provided as adjacent insets. In the higher-magnification view of the right macrophage, note the rhomboidal, orange, hematoidin crystal. Wright-Giemsa stain; bar = 25 μm in the primary images and 12.5 μm in the higher-magnification images. B—Aggregates of extracellular material are also present (arrow). Wright-Giemsa stain; bar = 12.5 μm. C—An enlarged image of the extracellular material in panel B. Wright-Giemsa stain; bar = 12.5 μm.
Citation: Journal of the American Veterinary Medical Association 255, 1; 10.2460/javma.255.1.67
Formulate differential diagnoses from the history, clinical findings, and Figure 1—then turn the page→
Additional Clinical and Cytologic Findings
In addition to the lytic lesion in the distal region of the left femur, radiography also revealed 2 radiopaque, metallic, thread-like structures in the right caudal portion of the abdomen. With consideration of the dog's history of prior abdominal surgery, these radiopaque metallic strands were consistent with retained surgical sponges. Cotton fibers from sponges are birefringent, a feature that may be readily observed when cytologic and histologic specimens are examined with polarized light. With the application of polarized light on the aspirate specimen obtained from the caudal abdominal mass, extracellular and intracellular aggregates of material were birefringent (Figures 2 and 3), as were hematoidin crystals, findings that were similar to those of other cytologic reports of gossypibomas in the literature.1
Same microscopic views of the mass aspirate specimen in Figure 1, as viewed under polarized light. The phagocytosed and extracellular cylindrical material is birefringent. A—Hematoidin crystals are yellow to orange and birefringent in this view (right macrophage), whereas the foreign material is generally a blue or pink color (left macrophage). Wright-Giemsa stain; bar = 25 μm in the primary images and 12.5 μm in the higher-magnification images. B—Extracellular material is also a blue or pink color (arrow). Wright-Giemsa stain; bar = 12.5 μm. C—An enlarged image of the extracellular material in panel B. Wright-Giemsa stain; bar = 12.5 μm.
Citation: Journal of the American Veterinary Medical Association 255, 1; 10.2460/javma.255.1.67
Photomicrographs of occasional long, thread-like fibers of uniform width in the mass aspirate specimen in Figure 1, as viewed under polarized light. In panels A and B, the threads appear birefringent. Wright-Giemsa stain; bar = 100 μm in each panel.
Citation: Journal of the American Veterinary Medical Association 255, 1; 10.2460/javma.255.1.67
Interpretation and Case Summary
Interpretation: granulomatous inflammation with extracellular and phagocytosed foreign, birefringent material (consistent with fibers from retained surgical sponges) and evidence of chronic hemorrhage.
Case summary: incidental gossypiboma in the abdomen of a dog.
Comments
Following the diagnosis of a femoral sarcoma, the owner elected palliative care for the dog of the present report with the option to follow up with the hospital's oncology service if desired. Because the dog had no clinical signs related to the caudal abdominal mass, no further diagnostic workup was pursued.
Radiographic and cytologic findings in the case described in the present report were consistent with a gossypiboma or textiloma. The term gossypiboma is derived from the Latin word gossipium, meaning cotton, and the Swahili word boma, meaning place of concealment. Similarly, the term textiloma is a descriptive term that is commonly used for this type of retained foreign object.2,3
Contaminant fibers (for example, gauze or cloth fibers from a sampling or slide processing environment) may be observed cytologically, but are not associated with inflammatory cells. In contrast, the fibers in the dog of the present report were associated with a granulomatous inflammatory response and were observed intracellularly within macrophages. The cotton fibers used in surgical sponges are made of natural polymers of cellulose, which are indigestible by tissue macrophages. Although any foreign material has the potential to incite a host inflammatory response, the magnitude and severity of that response are variable, depending on the size and type of the foreign material. It has been shown experimentally that even microscopic fragments of sterile sponge fibers may incite a foreign body response with multinucleated giant cell macrophage infiltrates in Wistar rats.4
When polarized light is transmitted through cotton, the light is split into perpendicular rays, which move through the cotton at 1 of 2 speeds. These light rays interfere with each other when they pass through a second polarizer, thereby creating new interference colors that correspond to the crystalline structure of the cotton fibers.5
Two types of gossypibomas are reported in the human medical literature: an acute or exudative type and an aseptic, chronic type.6 With the acute form, an exudative reaction develops rapidly, often over a period of days, and may lead to serious sequelae, including sepsis, intestinal obstruction, formation of fistulas to the skin or into surrounding viscera, and even death. With the aseptic chronic form, a fibrinous reaction results in encapsulation of the foreign material and formation of a granuloma. The granuloma may induce nonspecific or no clinical signs.6,7 In humans with long-term retention of a surgical sponge, the time from implantation to evaluation can span years to decades; to date, the longest reported elapsed time to evaluation is 50 years.8 In the dog of the present report, the gossypiboma was not associated with clinical signs, and it was discovered as an incidental finding 2 years following surgery. Although there are few reported cases of gossypibomas in the veterinary medical literature, associated serious complications have included osteomyelitis, visceral infiltration, and malignant transformation of surrounding tissues.8 Interestingly, there are several case reports9–11 of extraskeletal osteosarcomas associated with retained surgical sponges in dogs. These are rare malignant neoplasms that originate from the viscera or soft tissues and are characterized by production of osteoid without bone involvement.9 The precise mechanism for malignant transformation of viscera or soft tissues to extraskeletal osteosarcoma is unknown, although the veterinary medical literature suggests that niduses of chronic inflammation may contribute to sarcoma development.10,12 Following initial radiographic evaluation in the case described in the present report, it was speculated that the left distal femoral lesion could have been a metastatic lesion from an extraskeletal osteosarcoma associated with the observed retained surgical sponges, although this was not supported by the cytologic findings.
Although sponge and instrument counts are generally performed to prevent inadvertent nonretrieval of those items from surgical sites, retention of sponges can occur despite seemingly accurate counts and is more common in emergency procedures.7 The true incidence of gossypibomas is unknown, in part because of the fact that the chronic form is not accompanied by clinical signs. Some authors believe that reluctance to report such lesions among surgery personnel because of possible litigation may further mask the true incidence of gossypibomas.7 In human medicine, estimates of the incidence of gossypibomas range from as low as 1 of 18,760 surgeries to as high as 1 of 100 surgeries.7,13,14 Gossypibomas appear to be rare in veterinary medicine, with few published case reports and case series.8
Differential diagnoses for gossypibomas include granulomas from other causes, abscesses, cystic masses, and neoplasms. Traditionally, radiography has been used to aid in detection of retained surgical sponges and is particularly useful when surgical sponges are impregnated with radiopaque threads, as were those used in the case described in the present report. Radiopaque threads can become twisted and distorted over time, thereby complicating their interpretation in radiographic views. The threads may be mistaken for surgical sutures, wires, or nasogastric tube markers.13 Radiographically, the appearance of gossypibomas that lack radiopaque markers can be quite variable and may be nondescript. Some gossypibomas have been described as having a characteristic whirl-like appearance on plain radiographic views that results from gas entrapped in surgical sponge fibers.7,15 Ultrasonographically, these masses may appear as hypoechoic masses with echogenic centers that correspond to the retained foreign material and may attenuate sound waves, leading to development of an acoustic shadow, as was found for the dog of the present report.7,13,16 In human medicine, CT is the most commonly used and most effective imaging technique for the diagnosis of gossypibomas. In CT images, gossypibomas appear as walled masses with a spongiform or whirling pattern and gas bubbles.7,13
A gossypiboma should be included in the differential diagnosis list when there are soft tissue masses or localized signs of pain in any animal that has a history of surgery in that general anatomic area. The case described in the present report illustrated the usefulness of cytologic examination of fine-needle aspirate specimens of a tissue mass in providing support for a diagnosis of gossypiboma.
Acknowledgments
The authors thank Drs. Miranda Vieson, Matthew Wallig, Ian Sprandel, and Jonathan Samuelson for technical assistance.
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