An exceptional case of xanthomatous infiltration of the musculoskeletal and integumentary systems.

Tendinous and subcutaneous xanthomas are most commonly associated with primary hyperlipidemia. Xanthomatosis caused by cholesterol deposition can be a high risk marker for cardiovascular disease related to premature atherosclerosis; thus, early recognition of this diagnosis may reduce mortality and morbidity. Achilles tendon involvement is most common, followed by the extensor tendons of the hand and elbow. We present an exceptional case of tendinous and tuberous xanthomas, with intraoperative and histologic correlation, in a 34-year-old female manifesting with xanthomatous deposits of nearly all ankle tendons, plantar aponeurosis, extensor tendons of the hands, and various locations within the integumentum. To the authors' knowledge, only four studies to date have focused specifically on imaging findings of multifocal xanthomas. Thus, the radiographic and MR imaging descriptions of xanthomas in this report further add to the existing literature by helping to identify imaging characteristics of this multifocal systemic disease. The diagnosis of this condition should alert the physician to the presence of a dyslipidemia that can be treated with dietary modifications and/or drug therapy.

Cancerous 'floater': a lesson learned about tissue identity testing, endometrial cancer and microsatellite instability.

A 46-year-old woman presented with endometrial cells on a pap smear and underwent endometrial curettage. The specimen revealed secretory endometrium and a possible endometrial polyp. In addition, a single 4 mm fragment of well-differentiated adenocarcinoma was found. Tissue identity DNA genotyping was performed and the adenocarcinoma tissue fragment showed a drastically different allelic pattern from that of the background endometrium. To confirm tissue contamination, genotyping of three other tumor specimens-probable sources for a contaminant-was performed but failed to identify a match. Without confirmation of contamination, a second endometrial curettage was obtained from the patient, in which similar adenocarcinoma tissue was once again found. Further workup demonstrated that the patient had a microsatellite unstable (MSI) endometrial adenocarcinoma by immunohistochemistry and molecular testing. The patient subsequently underwent staging surgery, which revealed an early-stage, well-differentiated endometrioid adenocarcinoma. This case study illustrates an uncommon, yet important caveat of tissue identity testing by DNA genotyping, where MSI instability can significantly alter the allelic pattern of DNA polymorphisms in the tumor genome, leading to erroneous conclusion regarding the tissue identity. Awareness of this phenomenon is crucial for a molecular pathologist to avoid interpretation errors of tissue identity testing in a cancer diagnostic workup.