Struma Ovarii : Strumosis

Comments:
Strumosis (Strumatosis): In rare cases, struma ovarii patients have mature thyroid tissue implants in the peritoneum, omentum, or pelvic lymph nodes - a condition referred to as strumosis or strumatosis. These implants are now thought to represent peritoneal metastasis from well-differentiated follicular carcinoma arising in struma ovarii.

This image from struma ovarii shows solid growth pattern where the microfollicles arranged back-to-back with no intervening stroma.