Keratosis pilaris (KP) is documented on physical exam as small, folliculocentric keratotic papules, often with surrounding erythema, distributed over the extensor surfaces of the proximal extremities. The skin has a rough, sandpaper-like texture on palpation and a stippled, gooseflesh-like appearance on inspection. Getting the description right matters because KP is a clinical diagnosis, meaning the physical exam note needs to clearly convey findings that distinguish it from acne, folliculitis, and other papular eruptions.
Primary Lesion Description
The hallmark finding is a small, firm, follicular-based papule. Each papule forms because excess keratin accumulates within the follicular infundibulum, creating a plug that distends the follicular orifice. That plug is composed of horny lamellae and frequently traps one or more coiled or twisted hairs beneath it. On close inspection, you can sometimes see the coiled hair shaft within the papule, and it can be extracted with a fine-gauge needle.
In your note, describe the primary lesion as: “multiple discrete, 1 to 2 mm, folliculocentric, keratotic papules.” If erythema is present around individual papules, add “with perifollicular erythema.” The papules are typically flesh-colored, but they can appear pink, red, or even hyperpigmented depending on skin tone. Color should be documented as observed.
Texture and Surface Findings
Palpation is a key part of the exam. The grouped papules create a characteristic rough, sandpaper-like texture over the affected area. This is often described as resembling a “nutmeg grater” or “gooseflesh.” The surrounding skin is frequently xerotic (dry), which is worth noting because it reflects the underlying keratinization abnormality and often coexists with other dry-skin conditions.
A useful phrasing for documentation: “Skin is rough and dry to palpation with a sandpaper-like quality over the affected distribution.”
Distribution and Symmetry
KP has a predictable distribution that helps confirm the diagnosis. The most common locations are the extensor surfaces of the proximal upper arms and the anterolateral thighs. The buttocks are also frequently involved. Document whether the distribution is bilateral and symmetric, which is typical.
Less commonly, KP appears on the face (especially the lateral cheeks in children), trunk, and distal extremities. When facial involvement is prominent, it may represent a specific variant. Note every affected body region in your exam, as the extent of involvement is relevant for grading severity and distinguishing variants.
Recognizing Clinical Variants
Not all KP looks the same, and several variants have distinct exam features worth documenting precisely.
Keratosis pilaris rubra (KPR) presents with a prominent erythematous component. The redness extends beyond individual papules into broader patches and tends to persist or worsen around puberty. It does not progress to scarring. Distribution can be widespread across the extremities.
Keratosis pilaris atrophicans (KPA) is the variant that does scar. Involvement is often localized to the face, and you may see small, depressed scars or atrophic changes around follicles. Documenting the presence or absence of scarring is critical for distinguishing KPR from KPA.
Erythromelanosis follicularis faciei et colli (EFFC) is characterized by fine follicular papules with perifollicular erythema on the cheeks, forehead, and neck. If you see this pattern, note both the papule morphology and the hyperpigmented background that gives the condition its name.
Distinguishing KP From Similar Conditions
The physical exam should include observations that rule out common mimics. Acne vulgaris produces comedones (open and closed), pustules, and papules that vary in size and may be tender. KP papules are uniform in size, non-tender, and lack comedones or pustules. Acne also favors the face, chest, and upper back rather than the proximal extensor extremities.
Folliculitis presents as clusters of erythematous papules or pustules centered on hair follicles, but the papules are typically inflammatory, sometimes with visible purulent material, and the patient often reports tenderness, itching, or a history of friction, shaving, or moisture exposure. KP papules are keratotic rather than inflammatory, and the surrounding erythema is milder. Folliculitis can occur on any hair-bearing area, while KP follows its characteristic proximal extensor distribution.
To make the distinction clear in your note, emphasize: the absence of comedones and pustules, the uniform size of papules, the keratotic (not inflammatory) quality of the plugs, and the bilateral symmetric distribution on extensor surfaces.
Associated Findings to Document
KP rarely occurs in isolation. It is strongly associated with atopic dermatitis, ichthyosis vulgaris, and generalized xerosis. During the exam, check for signs of these conditions: dry or fissured skin elsewhere, flexural eczema, hyperlinear palms, or fine scaling on the shins. Noting these associations strengthens the clinical picture and may change management. About 50% of children and 40% of adults have KP, with incidence highest in the first decade of life, so the age of the patient provides useful context as well.
Putting It Together in a Note
A complete physical exam description of KP might read: “Bilateral, symmetric patches of multiple discrete, 1 to 2 mm, flesh-colored, folliculocentric keratotic papules on the extensor surfaces of the proximal upper arms and anterolateral thighs. Skin is rough and dry to palpation with a sandpaper-like texture. Mild perifollicular erythema is noted. No comedones, pustules, or scarring are present. Surrounding skin is xerotic.”
Adjust this template based on what you actually see. If there is prominent erythema, note its extent and whether it is limited to perifollicular areas or more diffuse. If atrophic changes or scarring are present, document them and consider KPA. If facial involvement is present, specify the distribution on the cheeks, forehead, or neck. The goal is a description specific enough that another clinician reading your note could visualize the findings and arrive at the same diagnosis.