Gastrointestinal (GI) pathology is the study of the upper and lower digestive system; GI pathology is a sub-category of pathology which focuses on diseases of the gastrointestinal system.

Urology is the study of the urological and urogenital system. The urogenital system relates to or involves both the urinary and genital organs. 

 

Dermatology is the study of the skin, hair, and nails; dermatology pathology or dermatopathology is a sub-category of pathology which focuses on cutaneous (skin) diseases.
 

Hematology is the study of blood and blood-forming organs; hematopathology is a sub-category of pathology which focuses on blood diseases and disorders.