Case Report 1: Adenosarcoma of the Uterus

Today I looked at a TAH & BSO for Adenosarcoma which was identified on biopsy of a polyp in the uterus. Adenosarcoma is an entity which falls into the mixed mullerian tumour category with benign glands and sarcomatous stroma (which often appears quite low grade). And typically presents as a polyp as in this case.

The biopsy showed a polypoid structure with slit like glands surrounded by a cellular stroma with a more fibrous stroma in the background with appearances almost reminiscent of a phyllodes tumour of the breast. The characteristic feature of adenosarcoma is the so called cambium layer or periglandular cuffing where the stromal cells concentrate around the glandular component. Typically there is little mitotic activity and atypia. A mitotic count of 1 or more per 10 hpf will differentiate it from an adenofibroma. However in this case there were foci of increased mitoses and atypical nuclei.

Most are confined to the endometrium. A small number invade into the inner half of the myometrium and deep invasion is rare in the absence of stromal overgrowth. However in this case there were foci of stromal growth in the outer half of the myometrium which would represent a FIGO stage 1c. Adenosarcoma can recur if not identified initially which can happen due to it’s low grade appearance. However has a good prognosis when completely excised. Adenosarcoma with stromal overgrowth and deep myometrial invasion has a poorer prognosis with risk of recurrence and metastasis.

Sarcomatous overgrowth in adenosarcoma is defined as the presence of pure sarcoma usually high grade and without an epithelial component occupying at least 25% of the tumour. A mitotic count may be attempted but may not always be helpful because of the potentially low or no mitotic activity as well as variability from area to area. Even if the mitotic count is <2/hpf the presence of the characteristic architecture with condensation of the stroma is sufficient for the diagnosis.

The differential diagnosis includes adenofibroma, benign endometrial polyp and an adenomyomatous polyp.

Mixed mullerian tumours include:

  • Adenofibroma (Benign glands and stroma)
  • Adenosarcoma (Benign glands & malignant stroma)
  • Carcinosarcoma (Malignant glands & stroma)
  • Carcinofibroma (Malignant glands & Benign stroma – a contraversial entity)


Robboy’s. Pathology of the Female Reproductive Tract. 2nd Ed.

Dataset for histological reporting of uterine sarcomas. March 2011. RCPath standards and datasets.

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