Anatomic Pathology: Cytopathology

• Although very uncommon, metastatic malignant cells from nongynecologic sources may be detected in cervicovaginal cytology Pap tests.

• This case is an example of lobular mammary carcinoma metastatic to pelvic organs, including the urinary bladder and cervix. This is a difficult case. The major differential diagnosis is high-grade squamous intraepithelial lesion (HSIL). This cervical cytology slide has a very clean background and no other signs of human papillomavirus (HPV) infection (i.e., no evident squamous cell atypia) and the cells appear glandular (adenocarcinoma) rather than squamous.

• Recognizing specific cytologic features associated with certain types of neoplasms, in this case, a single file pattern and intracytoplasmic vacuoles, is helpful in reaching a correct diagnosis. Clinical history is also important; however, in the case in the photomicrographs, the history of breast carcinoma was not provided.

• Organs adjacent to the uterus and uterine cervix, e.g., the urinary bladder and colon, are other possible sources of carcinomas that may secondarily involve the gynecologic tract by direct invasion.

• Small cell carcinoma is also in the differential diagnosis. Immunocytochemical stains may help confirm the diagnosis.