The rendering of an “official” diagnosis of pityriasis rubra pilaris requires two elements: clinical observation AND a biopsy that “supports” a diagnosis of PRP.
Clinical observations of a trained dermatologist
When a yet-to-be diagnosed PRP patient is seen by a dermatologist, the scope of the symptoms may vary from a small persistent spot on the forehead to a torso engulfed in inflammation. Even when PRP was immediately suspected, a dermatologist will be reluctant to enter the diagnostic code L44.0 on a medical chart and make the diagnosis official. A supporting biopsy is essential. [Link to 2017 ICD-10-CM, Diagnosis Code L44.0]
Supporting skin biopsy
In the case of PRP, biopsies are a diagnostic tool that typically “rules out” alternate skin maladies. Multiple biopsies are quite common. As the patient’s PRP symptoms become more recognizable, and the list of alternate diagnoses dwindles, the dermatologist may specifically instruct the dermatopathologist to “look for evidence of PRP”. A dermatopathologist is a pathologist who specializes in issues related to skin disorders.
PRP patients and caregivers have yet to see a biopsy report that stated: Patient has pityriasis rubra pilaris. You can take it to the bank! Instead we read statements that are less absolute.
The biopsy concludes that the findings are “compatible with” or “support” the clinical observations of a dermatologist.
The “Official” PRP Diagnosis
Based on clinical observations and a supporting biopsy, the dermatologist enters the diagnostic code L44.0 into a medical chart. The journey continues.
There are so many variables impede a timely diagnosis of PRP.
What is the dermatologist’s experience with PRP?
✽ Saw it in med school in a text book
✽ Saw a patient during grand rounds
✽ Saw a patient being treated by another dermatologist
What symptoms are visible to the dermatologist?
✽ Within a week of onset, e.g., a dime-sized spot on a forehead
✽ A month after onset , e.g., side of face engulfed
✽ Inflammation that mirrors psoriasis or atopic dermatitis
How soon is a biopsy performed and what is the outcome?
✽ The biopsy “rules out” other skin maladies. no “smoking gun” to be found in a skin biopsy. There is no “Gotcha” moment.
✽ The biopsy concludes that the findings are “inconclusive with” or “do not support” the clinical observations of a dermatologist.
✽ The biopsy concludes that the findings are “compatible with” or “support” the clinical observations of a dermatologist and “clinical correlation” is recommended.
Misdiagnosis of PRP is a problem
The diagnosis of PRP is too often delayed when the presenting symptoms of red and itchy skin mimic the signs of psoriasis or eczema. Not only does the missed diagnosis delay proper treatment, but inappropriate treatments can also be initiated in the interim. The PRP Patient Registry currently identifies the misdiagnosis of 328 PRP patients.
2013 PRP Biopsy Survey
During the summer of 2013, the survey of 487 PRPers gathered responses from 256 who detailed their biopsy experiences.
✽ Dx with no biopsy ordered: 7.8%
✽ Dx with no contradictory biopsy: 45.3%
✽ Biopsy supported Dx: 23.4%
✽ Dx with no confirming biopsy: 23.4%