Scar endometriosis

Case contributed by Fadi Aidi


A young patient presented with chronic cyclic pelvic pain at the site of a previous CS incision done 3 years ago. Her physician palpates a superficial lump on examination and explained it as a hypertrophic scar.

Patient Data

Age: 30 years
Gender: Female

A subcutaneous nodule with irregular borders and heterogeneous echogenicity but predominantly hypoechoic. Cystic changes are seen peripherally. Few Doppler signals are noted.


There is a well-defined, lobulated margin rounded heterogenous non-calcified soft tissue subcutaneous nodule seen in the left lower abdominal wall lying on the lateral aspect of the left rectus muscle showing diffuse enhancement and with multiple small cystic spaces, measures about 24x20 mm. Features are suggestive of scar endometriosis.


There is a well-defined irregular shaped, lobulated margined heterogenous nodule seen in the deep subcutaneous region of the left anterior pelvic wall seen close to the lateral aspect of the previous cesarean scar.

It consists of a central small soft tissue/fibrotic component and peripherally-oriented multiple cystic spaces.

The lesion is seen lying on and abutting the left rectus sheath with a possible focal minimal adhesion to it without definite invasion.

Signal characteristics appear as central isointense to skeletal muscle on T1 and T2. Peripheral cysts show T1 and T2 hyperintensity suggesting blood components. Blooming is seen on T2* confirming blood component.

The lesion measures about 3x2.3x1.6 cm. The lesion shows intense homogeneous contrast enhancement of the central part.

Features are highly suggestive of scar endometriosis with a subacute hemorrhage within the cysts which could be representing endometriotic crypts.

Another similar smaller intramuscular nodule is noted seen within the lower-left rectus muscle measures about 7x7.5 mm.

Small left hemorrhagic ovarian cyst. Normal right ovary with the dominant follicle.


Origin of Tissue: Skin and subcutaneous area, lesion.

Clinical Diagnosis: Endometriosis.

GROSS DESCRIPTION: Specimen received fixed labeled with patient’s name consist of:

Piece of tissue measuring 5.5x3.5x2 cm covered by a piece of skin measuring 4.5x2.5cm. On cut sectioning firm grayish and yellowish in color.

Specimens submitted for processing accordingly: 2 Blocks.


SKIN AND SUBCUTANEOUS TISSUE, LESION: Features consistent with endometriosis.

No evidence of malignancy.

Case Discussion

Scar endometriosis is a relatively uncommon but well-known condition that could be the cause of chronic recurrent abdominal or pelvic pain.

Cesarean section scar is the most common site of extra pelvic endometriosis which may cause implantation of endometrial stem cells at the time of surgery.

Patients may be symptomatic or present with cyclic pain.

Imaging features may be non-specific, so clinical history is important.

The presence of blood components in an anterior abdominal/pelvic wall without other explanation highly suggestive of scar endometriosis.

Scar endometriosis may involve the superficial abdominal/pelvic wall or deeper layers commonly the rectus sheath.

An important differential diagnosis is a desmoid tumor which typically does not associate with cyclic pain for that imaging and clinical correlation is crucial.

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