Vascular malformations need clear diagnostic criteria

To guide treatment choices for vascular malformations (VMs), clinicians rely on the International Society for the Study of Vascular Anomalies (ISSVA) clinical classification system for diagnosing VMs.¹ However, a recent retrospective study casts doubt on the validity of both clinical and histopathological diagnoses of these entities, prompting authors to call for clear diagnostic guidelines that consider clinical and histopathologic factors, as well as imaging.

"In the current diagnostic workup," wrote authors led by Sophie E.R. Horbach, M.D., of the University of Amsterdam, "diagnoses are generally made clinically based on natural history and physical examination, usually combined with radiologic imaging." The study appeared in the November 2017 Journal of the American Academy of Dermatology.²

To avoid invasive procedures for benign entities such as VMs, physicians perform diagnostic biopsies only in atypical cases involving suspected tumors. However, "It is unknown whether routinely performed histopathologic examination is indeed unnecessary in the diagnostic workup."

To answer this question, Horbach and colleagues retrospectively reviewed charts of all patients with clinically diagnosed VMs who underwent therapeutic surgical resections at the University of Amsterdam between 2000 and 2015. For consistency, a blinded pathologist reclassified all resected samples (which surgeons routinely sent for histopathologic examination for research purposes) using current ISSVA criteria. Among 142 samples, investigators found discrepancies between the clinical diagnosis and the revised histopathologic diagnosis in 57% of (or 81) cases.

"The large discrepancy implies that the current diagnostic workup does not suffice." Because investigators found nearly as many discrepancies (79) between original clinical and histopathologic diagnoses, their study raises "doubts about the validity of both clinical and histopathologic diagnosis. Therefore, we believe that neither diagnosis can currently be considered as the gold standard."

Investigators surmised that some discrepancies stemmed from histopathology-related causes; e.g. Pathologists often observe minor histologic arterial or lymphatic components not apparent on physical examination or imaging. Other discrepancies stemmed from physician-related causes; e.g. The difficulty of clinically determining vessel types included in low-flow lesions, which were particularly prone to discrepancies in the sample. In multivariate regression analyses, factors that made complete discrepancy significantly less likely included increasing patient age, a diagnosis of combined low-flow vascular malformation, diagnostic uncertainty of the clinician and use of radiologic imaging.

Diagnostic discrepancies are clinically significant because incorrect diagnoses of VM subtypes could lead to inadequate treatment. Additionally, "Uniform diagnoses are essential when investigating treatment response in therapeutic effectiveness studies." Accordingly, authors call for additional diagnostic guidance alongside the existing ISSVA classification system. "Clinicians and pathologists need to work together to develop clear, standardized diagnostic criteria for vascular malformations for clinical assessment, imaging and histopathology as the first step toward a uniform diagnosis."

Regarding study limitations, its retrospective design meant that not all details needed were described in patient charts. Additionally, enrolling only patients who underwent surgical resection may have introduced selection bias.

REFERENCES:

1. Wassef M, Blei F, Adams DM, et al. Vascular anomalies classification: recommendations from the International Society for the Study of Vascular Anomalies. Pediatrics. 2015;136(1):e203-e214.

2. Horbach SER, Utami AM, Meijer-Jorna LB, et al. Discrepancy between the clinical and histopathologic diagnosis of soft tissue vascular malformations. J Am Acad Dermatol. 2017:77:920-929.