Background: Recently we reported the successful in vitro cultivation of prostatic epithelial and stromal cells from patients with benign prostatic hyperplasia and adenocarcinoma of the prostate by liquid biopsy. In that study we noticed monocytes that were colonized by prostatic epithelial cells; this was confirmed using a monoclonal antibody to prostate epithelial cells. We also detected a deleterious effect exerted on the monocyte cytoplasm by a process yet to be determined.

Aim: To develop a hypothesis that will explain the significance of monocytes colonized by prostatic epithelial cells in the pathogenesis of prostate adenocarcinoma.

Study Design: Retrospective analysis of images in the previous study. Place and Duration: Kilimanjaro Christian Medical University College, Tumaini University, Moshi, Tanzania. One month.

Results: We found that all monocytes viewed, without exception, contained intra-cytoplasmic prostatic epithelial cells and most of them presented with apparent cytopathology. The cytopathology presented as strand formation and shrinkage of monocytes. Often the loss of integrity of monocyte cytoplasm could be arbitrarily graded as little to complete loss of cytoplasm.

Conclusion: We hypothesize that epithelial cells invade monocytes and colonize the cytoplasm. Monocytes colonized by epithelial cells then participate in the metastatic process of the prostate adenocarcinoma to different parts of the body. We report for the first time, a monocyte colonized by an epithelial cell of the prostate gland. This could also be an unrecognized phenomenon with other types of cancers.