23/03/2020
The patient presented to the ultrasound department with sever lower abdominal pains with a palpable lump at the left lateral aspect of her c-section scar. The had complained that pain coincides with her menstrual cycle but of recent was especially tender after a vigorous gym session. The referring doctor was concerned about an ovarian cyst or an abdominal wall tear.
The ultrasound could demonstrate a normal uterus, ovaries, kidneys and bladder. Of note was an irregular, lobulated hypoechoic mass confined to the subcutaneous fat superficial to the intact re**us abdominus.
When colour doppler was applied to differentiate between and solid and cystic mass, internal vascularity could be demonstrated on colour doppler therefore suggesting a solid lesion. The sonographic features were suggestive of an abdominal wall endometrioma most likely implanted at the time of the C-Section.
A bit more information from radiopaedia on abdominal wall endometriomas / Scar endometriosis.
Scar endometriosis is a term given to endometriosis occurring in a Cesarian section scar. It can be located in the skin, subcutaneous tissue, re**us muscle/sheath, intraperitoneally, or in the uterine myometrium (within uterine scar).
Epidemiology
The reported incidence of abdominal scar endometriosis following Cesarean section is 0.03-0.6% 6.
Clinical presentation
Patients may complain of tenderness to palpation and a raised, unsightly hypertrophic scar. Most patients have cyclical pain (up to 70%) 5. The pain is usually intermittent and associated with the patient's menstrual cycle but it may be constant in nature. Some reports state that only as low as 20% of the patients exhibited cyclical symptoms. The overlying skin may be hyperpigmented due to deposition of hemosiderin. Some patients may be asymptomatic 4.
Pathology
It is thought to be caused by implantation of endometrial stem cells at the surgical site at the time of uterine surgery.
Radiographic features
For general imaging features of endometriosis: refer to the parent article.
Ultrasound
Sonographic features are not specific. A subcutaneous nodule having relatively irregular borders, a heterogeneous echotexture with internal scattered hyperechoic echoes surrounded by a hyperechoic ring of variable width, and vascularity may be present. Occasionally cystic changes may be present 6.
CT
Well-defined soft tissue nodule with heterogenous post-contrast enhancement and streaky appearance in the surrounding tissue.
MRI
The most sensitive imaging modality. Often accurately locates the lesion in relation to a previous C-section scar, with signal characteristics similar to that of background endometriosis.
https://radiopaedia.org/articles/scar-endometriosis