Pityriasis Rotunda
Pityriasis rotunda (PR) is an uncommon disorder of keratinization, but one with real clinical significance as a warning sign. It produces strikingly round or oval patches with sharp borders, covered by fine, tightly adherent scale and showing a change in pigment (usually gray-brown darkening in people with darker skin). PR is not simply a harmless skin finding. It is divided into two types, and Type I PR points directly to serious internal disease—most notably hepatocellular carcinoma (HCC), cirrhosis, pulmonary tuberculosis, chronic heart failure and adenocarcinomas of the digestive tract.
The underlying problem is disordered differentiation and keratinization of epidermal cells (dyskeratinization), triggered by humoral factors, chronic inflammatory cytokines or metabolic toxins released into the circulation by internal tumors and systemic disease.
- Type I (associated): Begins in adulthood (over 40) and is most common in darker skin (Fitzpatrick types IV–VI, with high rates in Southeast Asia and southern Africa). This type is directly linked to liver cancer, chronic liver disease, pulmonary tuberculosis and malnutrition.
- Type II (familial/idiopathic): Runs in families, starts earlier (under 40), occurs in lighter-skinned people and is not associated with underlying internal disease.
Recognizing Pityriasis Rotunda Clinically
The lesions of pityriasis rotunda have distinctive features that set them apart from other scaly skin conditions:
- Distinctive shape: Perfectly round or oval patches that look as if drawn with a compass, from 0.5 cm to more than 20 cm across, sharply separated from the surrounding normal skin.
- Surface: Dry, with fine, firmly attached scale and accentuated skin markings. There is no red, inflamed halo at the edge or in the base of the lesion.
- Pigment change: In Asian patients the patches are usually light brown, gray-brown or clearly hyperpigmented; lighter (hypopigmented) patches are less common.
- Distribution: Mainly on the trunk (abdomen, back, chest), thighs and buttocks. The face, forearms, lower legs, palms and soles are almost never involved.
- Symptoms: Usually neither painful nor itchy (at most a mild itch in cold, dry weather).
Pityriasis Rotunda vs. Tinea Versicolor vs. Tinea Corporis
| Pityriasis Rotunda | Tinea (Pityriasis) Versicolor | Tinea Corporis |
|---|---|---|
| Keratinization disorder / paraneoplastic or systemic disease | Overgrowth of Malassezia yeast | Dermatophyte fungi (Trichophyton, Microsporum) |
| Perfectly round/oval, very sharply defined | Irregular patches that may merge into large areas | Round with scalloped outline and a raised, advancing edge |
| Fine scale, no red inflammatory halo | Fine adherent scale, positive scraping (Besnier) sign | Vesicles and red papules at the edge, clearing in the center |
| KOH completely negative for spores and hyphae | KOH positive ("spaghetti and meatballs") | KOH positive (septate hyphae) |
| High risk of HCC (liver cancer), cirrhosis, tuberculosis | Benign, cosmetic concern only | Benign, contagious skin infection |
Diagnosis and Clinical Management at Haute-Derma
When we see a patient with pityriasis rotunda, Haute-Derma follows a thorough workup designed to rule out an underlying malignancy:
Dermoscopy and Exclusion of Fungal Infection
- Digital dermoscopy: We look for opaque white bands of scale along the skin furrows, a uniform pigment network, mild loss of follicular openings within the lesion, and a complete absence of dotted vessels or inflammatory telangiectasia.
- KOH microscopy: Skin scrapings must always be examined under the microscope. A result negative for spores and hyphae is a key criterion for excluding tinea versicolor and tinea corporis.
Invasive Cosmetic Procedures Are Contraindicated
- No lasers or high-strength chemical peels: We do not use ablative lasers, Q-switched lasers for pigment, or strong acid peels on PR patches. Because the condition is tied to systemic disease, the skin irritates easily and is at risk of long-lasting post-inflammatory hyperpigmentation (PIH) or slow-healing ulcers.
- Soothing and gentle descaling regimen:
- Mild topical keratolytics: urea 5–10% cream, lactic acid 5% or salicylic acid 2%.
- A low-strength newer-generation retinoid (adapalene/tazarotene), under a doctor's supervision, to normalize keratinocyte differentiation.
- Barrier repair with a moisturizer containing a physiologic lipid mix (ceramides, cholesterol, fatty acids).
Urgent Screening for Systemic Disease
For adult Vietnamese patients with new-onset PR, Haute-Derma immediately arranges referral to internal medicine and oncology to screen for:
- Liver cancer (HCC) and liver disease: Abdominal ultrasound, the liver tumor marker AFP, HBsAg and anti-HCV serology, and liver enzymes (ALT, AST, GGT).
- Tuberculosis and lung disease: A frontal chest X-ray, plus a QuantiFERON-TB Gold test if TB is suspected.
- Gastrointestinal cancer: CEA levels, with upper endoscopy or colonoscopy if there is weight loss or loss of appetite.
