# The utility of biopsy in pyoderma gangrenosum: a retrospective cohort study

## TL;DR

A study of 58 patients found that biopsies are not very helpful for diagnosing pyoderma gangrenosum, while a specific scoring tool performs better.

## Contribution

The study evaluates the diagnostic utility of biopsies and three scoring tools for pyoderma gangrenosum in a clinical setting.

## Key findings

- Biopsies contributed to diagnosis in only 38% of cases.
- The PARACELSUS scoring tool showed the highest sensitivity for diagnosing pyoderma gangrenosum.
- Histopathological findings in pyoderma gangrenosum are nonspecific and limited in diagnostic value.

## Abstract

Three scoring tools used for the diagnosis of pyoderma gangrenosum are compared and the role of biopsy in pyoderma gangrenosum diagnosis is examined using 51 cases. Biopsies have limited diagnostic value in pyoderma gangrenosum, while the PARACELSUS scoring tool has the greatest sensitivity for diagnosing pyoderma gangrenosum.

Pyoderma gangrenosum (PG) is a rare skin condition characterized by chronic, painful ulcerations. It is considered a diagnosis of exclusion, often resulting in diagnostic delay. Histological results in PG, even when biopsied despite a risk of pathergy, are nonspecific.

To examine retrospectively the utility of biopsies in the diagnosis of 58 patients treated for PG.

Medical records were reviewed to compare biopsy results versus the efficacy of diagnostic rating systems (Delphi, Su, PARACELSUS).

Among 58 patients, 26 (45%) underwent biopsies, with only 10 (38%) contributing to a PG diagnosis. As a single-centre and retrospective study, documentation style and sample size limit generalizability.

Given risk of pathergy, nonspecific histopathological findings and low sensitivity, in our opinion, based on this small sample size, biopsies have limited diagnostic value for PG.