We describe a 37-year-old patient who presented with right lower quadrant pain and intermenstrual bleeding. MRI demonstrated a 5 ϫ 5 cm lobulated mass centered in the right uterine wall interpreted as suspicious for malignancy. A total hysterectomy was performed, and the gross and histologic features were consistent with the diagnosis of a uterus-like mass. Uterus-like mass is a benign entity that can be found in a variety of organs, and is characterized by endometrium surrounded by smooth muscle. It is an extremely rare lesion with only approximately 15 cases reported in the current literature. There is a lack of imaging literature on this entity, which is primarily described in the pathology literature. Its histogenesis is uncertain, but is theorized to be metaplastic change, congenital anomaly, and/or heterotopia. However, given the MRI appearance in this case, we feel that uterus-like mass could be prospectively diagnosed or listed in a differential diagnosis.

PCR, genomic DNA isolation, and agarose gel electrophoresis are common molecular biology techniques with a wide range of applications. Therefore, we have developed a series of exercises employing these techniques for an intermediate level undergraduate molecular biology laboratory course. In these exercises, students isolate genomic DNA from the nematode Caenorhabditis elegans and use PCR to detect deletions in the C. elegans unc-93 gene. In advance of the exercises, wild-type and three different unc-93 deletion mutant strains are grown, harvested, and frozen by the instructor. In one approach, students isolate genomic DNA from each strain using a genomic DNA isolation kit and use agarose gel electrophoresis to analyze the DNA and to estimate its concentration. PCRs using primers directed to two different regions of the unc-93 gene are carried out on the genomic DNA from wild-type and mutant strains, and the PCR products are analyzed by agarose gel electrophoresis. Students analyze the gel to determine the approximate location and size of deletions in the three mutant strains. Alternatively, students may lyse single nematodes and carry out PCR in one laboratory session. These exercises should be easily adaptable to detection of well characterized deletions in any organism.