What are cystic lesions?

People who are not medical professionals are not familiar with what cystic lesions are, and patients with this disease need to be worried. Cystic lesions are benign lesions and have no possibility of becoming cancerous. The ovarian cysts, ovarian endometriosis, teratomas, and ovarian cystadenomas that we are familiar with are all benign lesions. This article introduces the relevant knowledge in this area. If you want to know more, let’s take a look.

CT diagnosis of female adnexal cystic lesions:

1. Inspection methods and techniques

In pelvic CT examination, adequate preparation of the gastrointestinal tract and a well-filled bladder are essential, which helps to display the normal structure of the pelvis and accurately judge the relationship between organs to avoid misdiagnosis. Routinely, 300 ml of contrast agent diluted to 1% to 1.5% excreted by the kidneys is taken orally 3 hours, 2 hours, and 1 hour before the examination. Using this method, most of the pelvic small intestine is well filled, and in some patients with faster excretion, the colon and (or) rectum can also be filled with contrast agent. Filling the rectum and sigmoid colon with the same dilution of contrast medium can make the anterior sacrum easier to identify, but this is not commonly used. When examining the female reproductive system, vaginal plugs should be used routinely to determine the condition of the vaginal vault and cervix. If lesions or suspected lesions are found in the pelvis, enhanced scanning can be performed to display the pelvic wall vessels, identify the nature of the mass, and/or understand the blood supply of the mass.

2. Benign lesions

(I) Ovarian cyst

Most ovarian cysts cause no symptoms. On CT, ovarian cysts appear as smooth cystic masses with uniform density and CT values ​​close to water; the cyst wall is thin and uniform with smooth edges; after enhancement, the cyst contents do not enhance and the cyst wall usually does not enhance either. Most ovarian cysts are single and generally small (less than 4 cm in diameter), but they may also be larger or have cysts in multiple ovaries or on both ovaries at the same time. CT cannot differentiate between serous cysts, follicular cysts, or corpus luteum cysts, but it can confirm acute hemorrhage of cysts because the density of the cyst increases during bleeding.

(ii) Ovarian endometriosis

It is common in infertile women aged 30 to 40 years old, with a clinical history of dysmenorrhea, most commonly in the ovaries. CT findings are as follows: 1. There are round or quasi-round lesions in the ovary, with a watery density or slightly higher than a watery density, and stratification can be seen, which is related to bleeding. 2. The lesions may be large, and half of them are bilateral. 3. The thickness of the cyst wall may be inconsistent and may be smooth or rough. But there are no nodules or masses. 4. The cyst and the surrounding adhesions form a curtain-like protrusion, with no clear boundary with the adjacent organs. 5. After enhancement, there is no obvious enhancement inside the capsule, but the capsule wall may have no or slight enhancement.

(III) Cystic teratoma

It accounts for about 10% to 15% of ovarian tumors and is mainly seen in women of childbearing age and rarely in prepuberty or menopause. The vast majority of cystic teratomas are benign, of which approximately 0.25% to 0.8% become malignant. CT manifestations are: 1. The tumor is a cystic or mixed density soft tissue mass containing fat, with a CT value lower than -40Hu. Sometimes fat-fluid stratification can be seen, and its contents can change position with gravity when the body position changes. 2. The tumor has high density like teeth or bones. 3. The edge of the lesion is smooth and has a clear boundary with the surrounding area; if the tumor shows cystic changes, sometimes shell-like calcification can be seen on the cyst wall. 4. If the lesion only appears cystic without characteristics of fat or calcified tissue, the CT findings are non-characteristic. 5. After enhancement, there is no obvious enhancement inside the capsule and on the cystic wall.

(IV) Ovarian cystadenoma

Ovarian cystadenoma is the most common benign tumor of the ovary. Serous cystadenoma is often unilocular, and its content is similar to simple fluid. CT shows uniform cystic low-density shadows, with thin cyst walls (mostly less than 0.3 cm) and uniform consistency; after enhancement, there is no obvious enhancement in the cyst wall or the cyst. Mucinous cystadenomas are often multilocular with uneven density; after enhancement, there is no obvious enhancement in the cyst wall or the cyst. The presence of papillary protrusions on the cyst wall is rare, but if present, borderline carcinoma or cystadenocarcinoma should be considered. Cystadenoma should be distinguished from functional ovarian cysts, hydrosalpinx, and parasalpingic cysts.

2. Ovarian and fallopian tube abscess

The differentiation between atypical ovarian and fallopian tube abscesses and neoplastic lesions has always been a difficult problem. Even if spiral CT is performed with multi-phase enhanced scanning to observe the blood supply characteristics of the lesion, it is generally believed that the enhancement method is not of much value in distinguishing the two. Through the analysis of 14 cases and combined with the literature, we believe that ovarian fallopian tube abscess has the following CT features:

(i) Pelvic masses: The edges of most masses are unclear and the shapes are irregular or oblong. Circular, oval or tubular low-density areas can be seen in the mass, often with septa. Tubular axillary hypodense areas often indicate pyosalpinx but can also be seen due to

Patients with hydrosalpinx due to tumor blockage, tubal ligation, or previous pelvic inflammatory disease. The abscess wall is often thick, and its inner edge is often regular or smooth. The presence of bubbles within the mass is the most characteristic sign of an abscess, but this sign is rare in fallopian tube abscesses. After enhancement, the abscess wall often has obvious ring enhancement, and the ring wall is relatively complete.

(ii) Changes in the structures around the mass Because it is an inflammatory lesion, the structures around the mass often undergo thickening, adhesion, displacement, etc., manifested as:

1. Thickening and anterior displacement of the fallopian tube mesentery: This sign only indicates that the pelvic mass originates from the ovary or fallopian tube. In addition to infectious lesions of the ovary and fallopian tube, it can also be seen in endometrial translocation or ovarian tumors.

2. Thickening of the uterosacral ligament: Posterior extension of adnexal or fallopian tube inflammation can lead to thickening of the uterosacral ligament and increased fat density around the sacrum and rectum. Combined with the forward displacement of the fallopian tube mesentery, it further suggests the diagnosis of adnexitis.

3. Involvement of the rectum and sigmoid colon: The inflammation and fibrosis caused by inflammation of the ovaries and fallopian tubes tend to extend posteriorly to the rectum, around the sigmoid colon and presacral fat. CT scans can show thickening of the walls of the rectum and sigmoid colon, narrowing of the lumen, increased density of surrounding fat, and unclear boundaries between the pelvic mass and the intestinal wall.

4. Involvement of the pelvic mesentery or mesentery: When the inflammation spreads to the pelvic peritoneum or mesentery, the pelvic small intestinal wall may thicken, the lumen may narrow, the fat density between the intestinal curves and around the bladder may increase, and a small amount of fluid may be seen in the rectouterine pouch.

5. Others: May be accompanied by ureteral dilatation, effusion, renal hilar lymph node enlargement, etc.

3. Ovarian Malignant Tumors

The most common are borderline ovarian cystadenomas, serous or mucinous cystic adenocarcinomas. The age of this group of cases is relatively high. According to statistics from a group of cases compiled by the author, the average age is about 55 years old. Ovarian cancer cells are easy to fall off, so they are often accompanied by intra-abdominal implantation, ascites, etc. Clinical laboratory tests show that tumor markers such as CA125 are often elevated.

CT manifestations:

1. The lesions can be unilateral or bilateral.

2. The tumors often have irregular contours, lobed edges, and often invade surrounding organs.

3. Cystic lesions are often combined with solid components. The cystic walls or intervals of cystic lesions are of varying thickness, and the inner wall of the cystic cavity may be uneven or have wall nodules. The solid part often appears as plaques or vegetable-like changes and may protrude inside and outside the cystic wall.

4. A small number of lesions have calcification (26%), showing sand-like or amorphous changes.

5. The solid part of the mass, cyst wall, septa and wall nodules can be seen to be enhanced, and the CT value increase is often above 25Hu.

6. The course of the disease is short but the range of lesions is wide. Often, the lesions have already spread and implanted into the abdominal cavity when they are discovered. Lymphatic or hematogenous metastasis is less common (10% and 5%).

7. In about 5.2% of cases, CT scans show unilateral or bilateral pleural effusion. Due to the invasion of the urinary tract, hydronephrosis can be seen in about 8.5% of cases, resulting in partial kidney non-secreting function.