Term should be restricted to lesions that are probably carcinoma but either lack definitive diagnostic features or are too small to be certain that they do not represent the edge of a benign lesion
It should not be used if the lesion is benign but just unusual looking
For small foci, immunohistochemistry is primarily useful to disprove cancer, not to prove cancer
Basal cells must not be present on immunohistochemistry
Racemase/AMACR staining may be helpful as an adjunct but its interpretation should always be secondary to that of the basal cell markers
Always decide before staining which glands you consider to make up the suspicious population and which are adjacent or surrounded normal glands
Detection of even rare basal cells in any of the glands of the suspicious population excludes carcinoma for the entire population
Absence of basal cells in a small focus of atypical glands does not prove carcinoma
Small negative foci may simply be a manifestation of sampling of a population of glands with variable/decreased numbers of basal cells
Absence of basal cells throughout a large, well sampled population with other features of carcinoma can be considered diagnostic
A diagnosis of ASAP will generally lead to repeat biopsies for a definitive diagnosis, if clinically appropriate
