The Use and Misuse of Fitzpatrick’s Skin Types

The murder of George Floyd in the United States by an on-duty police officer in the spring of 2020 was a seminal crime triggering a time of reckoning for society and medicine, including dermatology. ¹ Rising social justice movements subsequently gained broad public support and pressure to increase equity, diversity, and inclusiveness in our health care systems for combatting historic and ongoing structural systemic racism and cultural violence. Implicit to achieving these goals is the need to effectively support those who are victimized, disadvantaged, and/or marginalized. In dermatology, these movements have inspired intense academic interest with corresponding studies and publications that aim to highlight the extent of systematic racism in medical education, research, and clinical practice.

Individuals differ in myriad ways including, but not limited to, language, religion, ethnicity, race, gender, cultural practices, dress, physical behavior, and appearance, all of which have been the basis for discrimination throughout history. The appearance of our skin through its innate color has been, and is still readily used, to stereotype individuals and groups. In dermatology, this framework is pervasive, that is, “skin of color,” which presumably encompasses individuals who are not of the majority white Caucasian population in “Western” countries. This editorial is not meant to debate various social, political, legal, or other constructs for framing the best rational and defensible approach to defining those who are affected by systemic biases. Rather, it aims to appraise and contextualize one particular skin typology system that is widely used in dermatology.

To quantify the extent of underrepresentation amongst minority groups, many recent authors and investigators have adopted the skin typing system conceptualized by a New England-based academic dermatologist, Thomas Fitzpatrick. One of Fitzpatrick’s key papers on skin phototyping ² has now been cited almost 2,500 times (Web of Science, accessed 10 October 2021). Anyone’s “Fizpatrick skin type” can be easily determined on a six level scale from I through VI. This system is arguably the most widely used grading system in dermatology because of its conceptual simplicity, longstanding use, applicability, reproducibility, and apparent validity. Moreover, it does not require any special instrumentation or measurement device and can be done relatively quickly by clinical history and/or examination.

Careful review of the methodology and genesis of Fitzpatrick’s system reminds us that it was originally developed not for categorizing patients according to their skin color, but for assessing an individual’s skin reactivity to natural and therapeutic ultraviolet radiation. Specifically at its inception, the system was based on the historical recollection or self-prediction of how a person with “white” skin would react to sunlight in terms of acute burning and delayed tanning. ³ A matrix of four possible combined outcomes for burning (always, usually, sometimes, and never) and tanning (never, with difficulty, about average, and with ease) established the initial skin-reactive “phototype” scale from I to IV. This scale became useful for guiding the starting dose of ultraviolet phototherapy; the biophysical basis for the correlation between these four original phototypes and skin reactivity to UV light was presumed to be related to epidermal melanin, a potent UV chromophore.

Patients with non-white skin were belatedly included in the system, but due to the assumption they did not sunburn, combined with the difficulty in assessing tanning in those with “black” and “brown” skin, a separate assessment criterion was used for categorizing individuals beyond skin phototypes I-IV: thus were created phototypes V and VI, based on the visual appearance of an individual’s skin color.

Scientifically, the Fitzpatrick skin phototyping system is unfortunately flawed by the discontinuous and concurrent use of 2 separate sets of criteria for different ranges within the overall scale: namely, skin reactivity for four of the levels, and skin color for the remaining two. Nevertheless, this approach still proved to be a useful clinical guide for its intended purpose of estimating safe and efficient initial ultraviolet doses in phototherapy. Over time, dermatologists conflated UV phototyping with skin color largely because intuition and clinical experience supported the notion that the visual continuum of skin color roughly approximated these six ordinal UV phototypes.

Although our skin’s color can be measured objectively via optical instrumental colorimetry or spectroscopy, the separation of skin color per se into discrete, well-defined categories has not yet been validated. Can skin color really be conveniently, reliably, and easily separated into six or any other set number of discrete categories? And on what scientific grounds? By default and custom, Fitzpatrick’s skin phototyping system remains the leading method for indirectly imputing skin color as a phenotypic determinant of health and disease, but it is important to appreciate its inherent limitations and appropriate use, especially when undertaking prospective studies and contributing to the scientific corpus. Could the George Floyd moment lead to a new way forward in how we consider skin color based on sound and rigorous scientific principles while also understanding its profound social justice dimensions?