Histopathology

The following two histopathological classification systems are available for the diagnosis of vascular anomalies and vascular tumors:

• WHO Classification of Tumors of Soft Tissue and Bone, 4th Edition, 2013, IACR
• ISSVA Classification (issva.org)

Furthermore, numerous publications on the subject (see “Recommended literature”) are referenced here. While the WHO classification focuses more on solid tumors, the ISSVA classification provides a detailed categorization of vascular anomalies in general, including vascular tumors and vascular malformations. The ongoing development of routine clinical nomenclature, which is more in line with the ISSVA classification, and the nomenclature in histopathology, which is more in line with the WHO classification, have clearly diverged here. This sometimes has a negative impact on patient care. A re-organization of nomenclature in the interests of patient care would be desirable.

The classification of the clinical spectrum of vascular anomalies has expanded considerably in recent years and will continue to increase, not least as a result of scientific reviews of cases and new genetic information. Many of these clinically distinct entities show similar or overlapping histologic patterns, so that an accurate light microscopic evaluation that also takes account of clinical and imaging data is absolutely essential in order to provide a correct classification in the synopsis of the pathology report. For this purpose, histopathologists should be provided with as detailed information as possible with regard to the clinical picture and imaging findings.

• What is the clinical presentation (discoloration, history, temperature, when did it develop? fast growing? painful?, etc.)?
• Where exactly is the lesion located?
• How large is the complete lesion?
• Are there any existing radiological findings (suspected radiological diagnosis, contrast agent behavior, etc.)?
• If preoperative treatment has been performed (e.g. embolization), this should also be reported.

Only when these findings are viewed together with the histopathology can a correct diagnosis be made with certainty.