In the series of Atsusi et al, an incidence of 34.5% was found for the fundal type of adenomyomatosis which was ranked second in the gallbladder, with the segmental type as 63.5%, and 2% for the diffuse type. The mean age of patients was 55.4 years and the range was 22 to 84 years [4
]. The female/male ratio shows variation in different studies [3
]. A few cases have been reported in the pediatric age group (range 15 to 17 years). All of our cases were female and the mean age was consistent with that in the literature. The histogenesis of adenomyomatosis is controversial [2
]. First, the high rates of co-existence of adenomyomatosis with irritative conditions of the gallbladder such as chronic inflammation or cholelithiasis was remarkable, and it was suggested that it was a hyperplasic inflammatory lesion [4
]. Despite of being accepted as a hamartomatous lesion or pseudotumor [2
], it has been reported that it may cause a benign tumor [22
] or may be a pre-malignant lesion with the potential of developing into a malignant tumor in a few studies [18-21
]. As biliary stasis occurs in the segmental type, the co-existence with cholelithiasis is the highest at 88.9%. This co-existence has been reported as 47.4% in the fundal and diffuse types [4
]. All of our cases were fundal type adenomyomatosis, and they underwent laparoscopic cholecystectomy with the diagnosis of cholelithiasis.
There are no symptoms in adenomyomatosis of gallbladder except for a vague abdominal pain. The co-existence with cholelithiasis is another reason for its clinically silent characteristic and incidental detection after cholecystectomy [2
]. Our cases were operated for cholelithiasis, and abdominal ultrasonography revealed a fundal mass lesion in one of our cases.
Most cases with adenomyomatosis of the gallbladder are diagnosed preoperatively using radiological investigations. Ultrasonography is the method of choice as it is inexpensive and practical. Dilated intramural cystic glands which are seen as artifacts and echogenic focuses causing focal or complete thickening in the gallbladder on ultrasonography are important findings for the diagnosis and are accepted as satisfactory for the preoperative differential diagnosis [4
Fundal type adenomyomatosis is seen macroscopically as an intraluminal hemispheric mass in the fundus of the gallbladder. Section surfaces are hard and consist of gray-white tissue and between these, dilated cystic glands. Histological diagnosis is easy; it has distinguishing microscopic characteristics from other lesions. The cases with adenomyomatosis of the gallbladder have combinations of proliferated glandular lobules, cystically dilated structures, and smooth muscle cell bundles in the stroma which was composed of connective tissue. The proliferated glands are floored with cuboidal or cylindrical epithelial cells between dense interlacing smooth muscle cell bundles [1
]. These epithelial cells are positive for cytokeratin-7 and cytokeratin-20, similar to immunohistochemically normal biliary cells. The smooth muscle cell component is positive for alpha-smooth muscle actin [2
]. Our cases were assessed as fundal type adenomyomatosis with their macroscopic, microscopic and immunohistochemical characteristics. The differential diagnosis of fundal type adenomyomatosis consists of several lesions which cause wall thickness and which protrude into the lumen. The most dreaded is adenocarcinoma of the gallbladder. They are differentiated from adenomyomatosis with their infiltrative characteristics. Adenomas are benign tumors of the gallbladder requiring a differential diagnosis. Other common and protruding polypoid lesions of the gallbladder are adenomatous polyp, hyperplastic polyp, cholesterol polyps, and xanthogranulomatous cholecystitis. Neoplasms with mesenchymal origin such as neuroma, carcinoid tumor, leiomyoma, fibroadenoma, fibroma, and lipoma are other uncommon lesions requiring a differential diagnosis. Besides, metastatic diseases including malignant melanoma foci should be remembered in the differential diagnosis [1
Fundal type adenomyomatosis is usually medically treated if the diagnosis has been made radiologically. If there is no response to medical treatment, cholecystectomy is the treatment of choice [2
]. One of our patients was operated with the diagnosis of cholelithiasis and gallbladder adenoma. Incidental adenomyomatosis was found in the other two patients who were operated with the diagnosis of cholelithiasis.
In conclusion, the macroscopic and microscopic assessments of cholecystectomies which were performed for cholelithiasis in routine clinical studies are usually predictable. However, incidental fundal type adenomatosis may also be seen. Recognition of this rare entity is important because the similar characteristics with the adenoma and carcinoma of the gallbladder may confound the surgeons. These lesions should be kept in mind due to their rare potential of developing into benign or malignant tumor.