3.a.iii.2 Micro-Invasive Squamous Cell Carcinoma

Micro-Invasive Squamous Cell Carcinoma

Micro-Invasive Squamous Cell Carcinomas

Micro-Invasive Squamous Cell Carcinoma

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The diagnosis of invasive squamous cell carcinoma of the cervix is usually straightforward because of the size of the tumor and the destructive nature of the stromal invasion. However, micro-invasion arising from a high grade squamous intraepithelial lesion (squamous cell carcinoma in situ) can often be challenging to diagnose. A very useful criterion to diagnose small foci of stromal invasion is the presence of an irregular epithelial-stromal border with loss of the peripheral palissading. High grade intraepithelial lesions (squamous cell carcinoma in situ) usually display a smooth epithelial-stromal border with organized nuclear polarity along the basal membrane which creates a peripheral palissading effect. Sometimes, the invasive focus arising from an intraepithelial lesion can even be seen budding outward from the intraepithelial lesion through the basal membrane. The presence of a paradoxal maturation (reversed maturation) is also very useful in identifying stromal invasion. Paradoxal maturation is defined as an area where the malignant cells acquire more abundant eosinophilic cytoplasm and have more atypical nuclear features. Finally, the presence of a stromal reaction and inflammation can be a clue to the presence of invasion. However care should be taken not to overdiagnose stromal invasion based solely on the presence of these two features as the uterine cervix often shows inflammation and reparative changes, especially following a biopsy.

Two staging systems have defined micro-invasion in the uterine cervix. The Society of Gynecologic Oncologists (SGO) defined micro-invasion as equal to or less than 3.0 mm in depth without capillary-space invasion. Whereas the Federation Internationale de Gynecologie et Obstetrique (FIGO) defined it as less than 5.0 mm in depth and 7.0 mm in length (tumor size). Having said that, measuring depth of invasion and tumor size can be challenging in some cases, especially when the tumor is multifocal or admixed with in situ carcinoma or when there is tangential inclusion of the specimen. For more information on how to measure depth and size of cervical carcinomas, see our tutorial on morphometry (coming soon).