The 5 P's of Pyoderma Gangrenosum

December 2019 | Volume 18 | Issue 12 | Features | 1282 | Copyright © December 2019

Brett C. Neill MD,ª Edward W. Seger MS,ª Tyler A. Hooton BS,ª Gabrielle Bailey BS,ª Anand Rajpara MD,ªWilliam V. Stoecker MD MSb

ªDivision of Dermatology, University of Kansas Medical Center, Kansas City, KS 

BDepartment of Dermatology, University of Missouri, Columbia, MO 

*This work won First Place in the 9th Annual ARTE Poster Competition at ODAC.

The diagnosis of pyoderma gangrenosum (PG) is often difficult to establish based on a clinical presentation, which can mimic other dermatologic conditions. The formation of a mnemonic that incorporates the most prevalent clinical features of PG could aid in accuracy and speed of diagnosis. The 5 P's of PG: Painful, Progressive, Purple, Pretibial, Pathergy, and systemic associations, incorporate parameters recognizable on the first encounter with a patient with PG without reliance on histopathology and laboratory findings or treatment response. We postulate that this simple mnemonic will have the most utility with non-dermatology clinicians encountering a lesion suspicious for PG. By assisting in differential diagnosis formation, this mnemonic may lead to timelier biopsies and treatment initiation. The limitations of this approach mirror those of other studies and include lower sensitivities in patients with an atypical PG presentation. In conclusion, the 5 P's of PG offer a useful mnemonic for the diagnosis of PG, particularly in the initial clinical diagnosis prior to skin biopsy and treatment.

J Drugs Dermatol. 2019;18(12):1282-1283.


Pyoderma gangrenosum (PG) is an inflammatory neutrophilic dermatosis which is often difficult to diagnose because of a clinical presentation which frequently mimics conditions such as infections, vascular diseases, and malignancies.1 Recently, several studies have attempted to define the prevalence of clinical manifestations of PG in order to improve diagnostic accuracy.2-4 Utilizing these reports, we offer for consideration a mnemonic of the clinical features of PG, the 5 P's of PG: Painful, Progressive, Purple, Pretibial, Pathergy, and systemic associations (Table 1). This set of key clinical parameters is recognizable on the first encounter with a patient with PG and is modeled after the widely used 6 P’s of lichen planus (planar, purple, polygonal, pruritic, papules, and plaques).5 Our mnemonic incorporates the most sensitive features from compressive diagnostic algorithms and does so without reliance on histopathology and laboratory findings, co-morbidities, or treatment response.4,6 Moreover, the addition of “pretibial” reminds us of the most common location of PG: 78% of patients reported by Binus et al7 and 62% of patients reported by Ashchyan et al8 had lesions on the legs.