A case report of rare intraperitoneal cholesteatoma diagnosed and treated through multidisciplinary collaboration

Abstract 55‐year‐old female patient with abdominal distension and poor appetite for 3 months was diagnosed as intraperitoneal cholesteatoma by imaging findings and histological tests. Patient has received surgical resection and recovered well after operation.


AND REVIEW
Combined with the existing examination results, the nature of the abdominal space-occupying lesion could not yet be determined. However, the symptoms of patient such as abdominal distension and anorexia are further aggravated, which indicates that the abdominal cavity space-occupying lesion and oppresses the surrounding organs and tissues seriously. After discussion, an exploratory laparotomy was planned to relieve the compression and confirm the diagnosis. After performing the relevant preoperative examinations within 1 week of admission, exploratory laparotomy was performed under general anesthesia. Along the 25 cm right paramedian abdominal incision, the abdominal mass (15 × 15 × 10 cm, see Figure 2A) was fully exposed after layerby-layer laparotomy. The capsule of the mass was intact with high tension. The surface of the mass showed local yellowish-white changes, and the mass was tough, with a poor blood supply. The explored mass originated from the right ovary and had no adhesion with the surrounding organs. There were several ectopic proliferative masses (several masses were on the greater omentum or free, one mass was on the diaphragmatic surface of the spleen, two masses were on the diaphragmatic surface of the liver, and one mass was on the right posterior lobe of liver). Bilateral adnexectomy + hepatosplenic ectopic hyperplasia resection + enterolysis were performed, and all masses detected in the abdominal cavity were completely removed. Intraoperative specimen dissection was performed, and numerous lesions with "pearl-like" tumor characteristics contained light yellowish fluid (see Figure 2B). Histological examinations showed "pearly tumors" with sizes of approximately 4-6 mm. The surface was covered with mesangium, which contained tiny blood vessels (see Figure 2C). The pathological examination also revealed that the cyst wall was covered with stratified squamous epithelium, and a keratinized substance was visible within the cyst (see Figure 2D,E).
CT was performed 7 days after the operation. The liver changed after the operation; the punctate high-density shadow visible in the upper segment of the right lobe of the liver was no longer present, and the patchy low-density shadow visible in the liver had been resected. The cystic low-density shadow visible in the right abdominal cavity had been resected. The spleen showed postoperative changes. The multiple ring shadows visible in the intestinal canal of the right lower abdomen were no longer visible, and the bilateral adnexa had been removed.

| DISCUSSION
Cholesteatoma is a benign tumor, which is an enlarged collection of keratins in a squamous epithelial sac. Because the tumor contains abundant keratins, cholesterol, lipids, calcification and other substances, the appearance of the cyst wall is thin, white and lustrous, and translucent, and the cyst has F I G U R E 2 Pathological examination results of the mass. A, Dissection of the surgical specimen showed a cyst with a size of 15 × 15 × 10 cm, of which the capsule was complete with high tension. The surface showed local yellowish-white changes. The mass was yellowish-white, and the texture was tough and hard. The length of the oviduct tissue was 12.5 cm, and its diameter was 0.8 cm. B, The thickness of the cyst wall was 0.2-1.5 cm, and inside the cyst, there were several grayish white nodules with diameters of 0.1-0.7 cm and a large amount of fluid (approximately 2000 ml). C, Pathological examination results showed "pearly tumors" with sizes of approximately 4-6 mm. The surface was covered with mesangium, which contained tiny blood vessels. See Figure e for the tissues inside the mesangium. D, The outermost cyst wall tissue, in which blood vessels and skin appendages were visible. E, The structure under the mesangium of the "pearly tumor": stratified squamous epithelial cells, in which keratinized protein was found a pearl-like shape with a clear boundary. Cholesteatomas do not have an abundant blood supply and have various sizes; they are known as "pearly tumors". 8,9 Due to the different ratios of squamous epithelial debris and keratinized protein in the cyst, the lesion can cystic or pseudo-solid, which results from the etiology (congenital or acquired). 1 In addition, most cases occur in the middle ear, mastoid process, cerebellopontine angle, suprasellar cistern, skull and temporal bone and other parts of the body 10 ; intraperitoneal cholesteatoma is very rare and rarely reported in the literature in China and abroad.
Under MRI, cholesteatoma is mainly shown as hypointense on T1-weighted images and hyperintense on T2weighted images without significant enhancement, and diffusion-weighted imaging (DWI) is an effective method for differentiating cholesteatoma from other cystic lesions. [11][12][13] A study by Williams et al found that cholesteatoma is avascular and cannot be enhanced with contrast agent in MRI, 14 whereas granulation tissue is poorly vascularized and is enhanced on delayed imaging. Studies by Schwartz et al found that cholesteatoma showed high intensity in DWI because of limited water fusion and partly because its keratin content produced high signal intensity in the T2 penetrating effect area of the diseased tissue and that the high signal intensity of cholesteatoma in DWI images had a higher diagnostic accuracy. 15,16 In the diagnosis of primary, residual, or recurrent cholesteatoma, the assessment of DWI is objective and reliable. In recent years, studies by Atsushi Fukuda and other scholars found that a high concentration of protein, 17,18 not cholesterol and triglyceride content, is the cause of high signal intensity in T1-weighted images of cholesteatoma.
According to pathology, whether the cholesteatoma is congenital or acquired, they manifest as cystic, variably sized, white to pearly masses containing creamy or waxy material. In the histological diagnosis, when stratified keratinized squamous epithelium, subepithelial fibrous connective tissue or granulation tissue, and keratin debris are observed by microscopy, it can be concluded that the cyst content is composed of exfoliated epithelial cells and cholesterol crystals. [19][20][21]