A Rare Collision Tumour of Uterus- Squamous Cell Carcinoma and Endometrial Stromal Sarcoma

Collision tumours are defined by co-existence of two tumours in the same or adjacent organs which are topographically and histologically distinct with minimal or no histological admixture. Collision tumours have been described in many organs notably thyroid, brain, adrenal gland, stomach and rarely uterus. Most of the collision tumours reported in uterus have two components; an adenocarcinoma and a sarcoma. We report a case of a 60-year-old lady who presented with complaints of post-menopausal bleeding. A cervical biopsy was performed which showed a non-keratinizing squamous cell carcinoma of cervix. Intra-operatively the uterus was bulky with a 6 cm x 5 cm polypoidal mass in the endometrial canal along with a 2 cm friable cervical growth. The fleshy uterine cavity mass was a spindle cell tumour with moderate pleomorphism and frequent mitosis. It was immunopositive for CD10 and negative for smooth muscle actin and cytokeratin 5/6. The other growth showed non-keratinizing squamous cell carcinoma which was positive for cytokeratin 5/6. Based on the distinct topographical location and limited areas of tumour admixture of the two tumours, a diagnosis of collision tumour of uterus comprising of endometrial stromal sarcoma (high grade) uterus and squamous cell carcinoma cervix was made.