Microinvasive squamous cell carcinoma
The term ‘microinvasive’ was usually used as a synonymous of pT1a1 in TNM staging system. The criteria of pT1a1 are the following: 3 mm. maximum depth of invasion, maximum horizontal spread – 7 mm. The same criteria are taken by College of American Pathologists (CAP) in their Pathological Protocols which are based on AJCC/UICC TNM 6th edition and FIGO 2001 Annual Report. From the other hand the last edition of WHO tumour classification recommend the use of FIGO staging which individualize two types of lesions, IA1 described above and IA2 lesion (max. depth 5 mm. and horizontal spread 7 mm). See the TNM and FIGO classifications.