Decidua and squamous metaplasia in abdominopelvic lymph nodes.

We describe two variants of benign para-aortic lymph nodal inclusions that mimic squamous cell carcinoma. The first, a decidual reaction, occurred in a 27-year-old pregnant woman with squamous cell carcinoma of the cervix. The second, a squamous metaplasia of ectopic müllerian-type glands, was present in a 63-year-old woman with squamous cell carcinoma of the anus. Intranodal decidua has been described, but squamous metaplasia of glandular inclusions has not been previously reported. Müllerian-type nodal inclusions are reviewed, and histologic features distinguishing decidua and squamous metaplasia from carcinoma are discussed.