Final answer:
Endometrial adenocarcinoma is the most common histological diagnosis found in patients with AGUS, while squamous cell carcinoma is a less likely association.
Step-by-step explanation:
The most common histological diagnosis found in patients with AGUS (atypical glandular cells of undetermined significance) is endometrial adenocarcinoma. AGUS is a term used to describe abnormal glandular cells from the endometrium or endocervix that are found on a Pap smear but are not sufficient to make a definitive diagnosis. Although there are several potential underlying conditions associated with AGUS, endometrial adenocarcinoma is frequently diagnosed upon further investigation. Therefore when a patient presents with AGUS, a more thorough evaluation including an endometrial biopsy may be necessary to rule out or confirm this diagnosis.
Squamous cell carcinoma is another type of cancer usually involving the squamous cells in the epidermis and is not the most common diagnosis associated with AGUS. This type of carcinoma often presents as lesions on the skin and is not directly related to the glandular cells of the cervix or endometrium.