Pityriasis Rosea and Tinea Infections are easy to mix up on the boards. Here's a side-by-side comparison — presentation, workup, imaging, and first-line treatment — drawn from our full outlines.
Pityriasis Rosea vs Tinea Infections at a glance
Pityriasis Rosea: Self-limited papulosquamous eruption with herald patch and Christmas-tree distribution; likely HHV-6/7 reactivation.
Tinea Infections: Superficial dermatophyte (and Malassezia) infections of skin, hair, and nails with site-specific presentations.
Try two board-style questions on Pityriasis Rosea vs Tinea Infections
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Question 1DermatologyEasy
A 22-year-old woman has a 10-day history of numerous salmon-colored oval plaques with fine scale scattered over her trunk. The long axes of the lesions run parallel to the ribs. The eruption is mildly itchy, she feels well, and there are no lesions on the palms or soles. Which of the following is most likely to be found on further examination?
AFine white lacy streaks on the buccal mucosa bilaterally
BA single larger plaque with a trailing collarette of scale
CPinpoint bleeding after the scale is scraped from a lesion
DMoist gray-white flat plaques in the perineal skin folds
Reveal answer & full explanation
Correct answer: B — A single larger plaque with a trailing collarette of scale
AFine white lacy streaks on the buccal mucosa bilaterally
BA single larger plaque with a trailing collarette of scale✓
CPinpoint bleeding after the scale is scraped from a lesion
DMoist gray-white flat plaques in the perineal skin folds
Why A single larger plaque with a trailing collarette of scale is correct
Multiple oval salmon-colored plaques with fine scale distributed along the lines of skin cleavage on the trunk, producing the Christmas-tree pattern on the back, is pityriasis rosea.
In 50-80 percent of cases the eruption is preceded by 5-15 days by a single larger lesion, the herald patch, most often on the trunk, with a characteristic trailing collarette of scale attached at its outer edge and free centrally.
Patients frequently mistake the herald patch for ringworm, and finding it retrospectively secures the diagnosis.
Human herpesvirus 6 and 7 reactivation is the leading proposed cause.
The eruption is self-limited over 6-8 weeks and needs only reassurance, emollients, and antihistamines for itch.
Why the others are wrong
Moist gray-white flat plaques in the perineal skin folds — condylomata lata of secondary syphilis. This matters because secondary syphilis is the great mimic of pityriasis rosea, so any patient whose eruption involves the PALMS AND SOLES, or who lacks a herald patch, or who has mucosal lesions or lymphadenopathy, needs syphilis serology.
Pinpoint bleeding after the scale is scraped from a lesion — the Auspitz sign of psoriasis, whose plaques are thick, silvery, and symmetric on extensor surfaces.
Fine white lacy streaks on the buccal mucosa bilaterally — Wickham striae of lichen planus, which produces violaceous flat-topped papules on the flexor wrists.
Question 2DermatologyMedium
A 19-year-old man presents in late summer with several weeks of asymptomatic, finely scaling macules on his upper back, chest, and shoulders. He says the patches did not tan with the rest of his skin and appear lighter than the surrounding area. He plays on a club soccer team and showers in a communal locker room. Examination shows multiple hypopigmented, fawn-colored macules with fine scale that becomes more apparent when the skin is gently stretched. A scraping of the scale is examined under the microscope after potassium hydroxide preparation. Which of the following microscopic KOH findings best supports the diagnosis?
AShort hyphae mixed with round budding yeast cells
BLong branching septate hyphae without budding cells
CClusters of round budding yeast cells without hyphae
DBudding yeast cells together with elongated pseudohyphae
Reveal answer & full explanation
Correct answer: A — Short hyphae mixed with round budding yeast cells
AShort hyphae mixed with round budding yeast cells✓
BLong branching septate hyphae without budding cells
CClusters of round budding yeast cells without hyphae
DBudding yeast cells together with elongated pseudohyphae
Why Short hyphae mixed with round budding yeast cells is correct
The vignette describes tinea (pityriasis) versicolor: hypopigmented, fawn-colored, finely scaling macules on the upper trunk of a young adult, with scale accentuated on stretching.
It is caused by the lipophilic yeast Malassezia furfur, whose conversion to the mycelial form produces disease.
KOH preparation classically shows short, stubby hyphae intermixed with clusters of round yeast cells — the "spaghetti and meatballs" appearance — which is the discriminating finding.
Malassezia produces azelaic acid that inhibits melanocytes, explaining the failure of involved skin to tan.
Why the others are wrong
Long branching septate hyphae without budding cells — this is the KOH pattern of true dermatophyte (Trichophyton/Microsporum/Epidermophyton) infections such as tinea corporis, cruris, or pedis, not versicolor.
Clusters of round budding yeast cells without hyphae — Malassezia in its yeast form is normal commensal flora of sebum-rich skin; disease requires conversion to the hyphal (mycelial) form, so yeast cells with no hyphae reflect colonization and do not confirm versicolor.
Budding yeast cells together with elongated pseudohyphae — this is the pattern of Candida, which causes intertrigo with satellite pustules and scrotal involvement, not finely scaling truncal macules.
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Self-limited papulosquamous eruption with herald patch and Christmas-tree distribution; likely HHV-6/7 reactivation.
Superficial dermatophyte (and Malassezia) infections of skin, hair, and nails with site-specific presentations.
Classic presentation
Herald patch + Christmas-tree distribution on trunk + collarette of scale on peripheral lesions.; Mild prodrome (50%): headache, malaise, low-grade fever, sore throat; Pruritus mild to moderate (25-75%), occasionally severe; Asymptomatic in many patients; Herald patch: 2-10 cm single oval, salmon-pink plaque with collarette of scale at…
Active raised scaly border with central clearing (corporis); KOH 'spaghetti and meatballs' (versicolor); Wood's lamp yellow-green fluorescence (Microsporum tinea capitis).; Pruritus (mild to moderate); Scalp scaling, hair loss (capitis); Burning, fissuring between toes (pedis); Cosmetic concerns (versicolor); Tinea corporis: annular…
Workup / key labs
Clinical: herald patch + secondary eruption in characteristic distribution + collarette of scale; self-limited course 6-8 weeks.; Clinical diagnosis; RPR/VDRL to exclude secondary syphilis in all sexually active adults; KOH of herald patch if tinea suspected; Skin biopsy rarely needed: spongiosis, parakeratosis in mounds, mild…
KOH and/or culture positivity in characteristic clinical setting.; KOH preparation of scale or hair: branching septate hyphae (dermatophyte) or short hyphae + spores ('spaghetti and meatballs') for versicolor; Fungal culture (Sabouraud or DTM agar) — confirms species, especially for capitis and onychomycosis before systemic therapy;…
Imaging
Not indicated
Not indicated
First-line treatment
Reassurance — disease is self-limited, resolving in 6-8 weeks (range 2 weeks to 3 months) without scarring; Symptomatic care for pruritus: emollients, low-mid potency topical corticosteroid (triamcinolone 0.1%), oral antihistamines (cetirizine, hydroxyzine for sleep); Oatmeal baths, calamine lotion for itch; Sun exposure or narrowband…
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