Pityriasis rotunda (PR) is a rare, idiopathic, and chronic dermatosis characterized by discrete, round, scaly, pigmented patches.[1, 2, 3, 4, 5, 6, 7, 8, 9] Pityriasis rotunda may be associated with systemic diseases (eg, hepatocellular carcinoma) in certain racially predisposed groups.
The pathophysiology of pityriasis rotunda is still not completely understood. It may be a variant of ichthyosis vulgaris. Some studies have reported lower expression of loricrin and filaggrin in lesional skin.[10, 11] Concomitant occurrence of ichthyosis vulgaris may indicate a potential etiological relationship.[12]
The cause of pityriasis rotunda is unknown. Some authors believe it is a variant of ichthyosis vulgaris because both have similar histologic findings.[13] Some authors believe pityriasis rotunda is caused by malnutrition, but this is not universally accepted.[14] In familial cases, an autosomal dominant mode of transmission has been proposed.[3, 15, 16, 17] The presence of systemic disease appears to be common in black South African and Japanese patients, but is much less likely among white patients.[18, 19, 20]
Black South African patients
In one series of 10 black South African patients with pityriasis rotunda, 7 had hepatocellular carcinoma. Pityriasis rotunda occurred in 15.9% of 63 unselected black South African patients with hepatocellular carcinoma, which is significantly greater than its prevalence in 63 matched controls with each of the following:
Active tuberculosis (4.8%)
Chronic benign hepatic disease (3.2%)
Other malignancy (0%)
In South African patients, pityriasis rotunda has also been associated with the following:
Chronic myeloid leukemia
Squamous cell carcinoma of the hard palate
Tuberculosis[21]
Liver disease
Cardiac disease
Nutritional disease
Various malignancies
Pulmonary disease
Chronic renal failure
Osteitis
Chronic diarrhea
Scleroderma
Resolution of pityriasis rotunda has been noted with treatment of the underlying malignancy.[22]
Japanese patients
In the report of 181 patients (largely Japanese) in the French-language literature, 4 cases were associated with carcinoma of the stomach, 3 with carcinoma of the liver, 1 with carcinoma of the lung, 3 with unspecified malignant tumors.
In the same series, one Japanese patient with pityriasis rotunda had multiple myeloma, while another had myeloma and hepatic cirrhosis.[23]
White patients
The association with systemic disease appears much less common among white patients. However, some cases are familial, suggesting an autosomal dominant pattern of inheritance.
In one Sardinian family, pityriasis rotunda occurred in 3 siblings, whose father had typical ichthyosis vulgaris.
In another Sardinian family, 5 of 18 affected individuals had favism (deficiency of glucose-6-phosphate dehydrogenase). Such an association is likely coincidental because favism is common among individuals from the family's place of origin.[15, 24]
American patients
Pityriasis rotunda has been reported in 7 African Americans. One patient had metastatic adenocarcinoma, one had diabetes and unexplained thrombocytopenia, while another had human T-cell lymphotropic virus type 1–associated tropical spastic paraparesis. The fourth had mild hypertension. The fifth and sixth patients did not have any associated medical conditions. The sixth patient had associated sarcoidosis.[1, 25, 26, 27, 28, 29]
Pityriasis rotunda is very uncommon in America. A review of English-language literature revealed only 6 case reports from America, which described 7 patients.[1, 25, 26, 27, 28, 29]
International
Pityriasis rotunda is a well-known condition in South Africa, Japan, and Italy, with the first known reported case from Japan in 1906.[7] Pityriasis rotunda was seen in 65 (1.01%) of 6388 South African medical inpatients. Japanese investigators reported 181 cases of pityriasis rotunda in 1960. Forty-two cases, all from the Italian island of Sardinia, were reviewed in 1997.[30] In 1989, one review of the English-language literature discussed 89 previously reported pityriasis rotunda patients. Cases of pityriasis rotunda have also been reported in Israel, England, Egypt, Portugal, Tanzania, and India.[2, 31, 32, 33, 34, 35, 36]
Race
Most cases of pityriasis rotunda are from South Africa, and all seven cases from America have occurred in blacks. Pityriasis rotunda in the South African Bantu population has been associated with hepatocellular carcinoma and malnutrition.[14, 37]
In the 1960 review of 181 cases in the French-language literature (performed by Japanese investigators), 175 patients were from Japan, 4 were from Korea, and 2 were from Manchuria.[38]
Cases have been reported among West Indians living in England.[33]
Other than the cluster of 42 patients (some familial) reported from the Italian island of Sardinia, pityriasis rotunda appears to be very uncommon among whites.[30, 39]
Sex
No sex predilection has been demonstrated in several large series, although some studies have noted a slight female predominance.[10] One series had 77 males and 63 females; another had 73 males and 101 females. A report of Sardinian patients had 22 males and 20 females.[30]
Age
Lesions are often first noted in adulthood, usually when aged 20-45 years, but a patient as old as 87 years has been reported.[10] In the review of 42 cases from Sardinia, the average age of onset was estimated to be 3-7 years.[30]
The prognosis for pityriasis rotunda is excellent. Pityriasis rotunda lesions sometimes resolve with treatment of the associated systemic disorder or malignancy. Lesions of pityriasis rotunda are not associated with mortality, and most are asymptomatic. Pityriasis rotunda can occur with serious underlying systemic diseases, such as hepatocellular carcinoma.[37, 40]
Pityriasis rotunda patients are usually asymptomatic. In one review of 64 cases, all patients were undergoing assessment for an underlying medical condition and the lesions of pityriasis rotunda were noted incidentally. Few could remember the duration of the lesions, which varied from 1 week to 2 years.
Two clinical types of pityriasis rotunda are described. Type 1 affects Asian or black patients older than 60 years old who tend to have associated malignancies or systemic disease. These patients present with few hyperpigmented patches (< 30) that are usually nonfamilial. Type 2 affects white patients younger than 40 years who do not have any associated malignancy or systemic diseases and who present with multiple hypopigmented patches (>30) that show familial incidence.[3, 41, 42]
Lesions range from pink to light-brown, are usually perfectly round but sometimes can be oval, and appear as well-demarcated patches that show fine scaling. They range from 0.5-20 cm and are generally isolated, but the merging of lesions results in a polycyclic configuration.
Several lesions are usually present, ranging from 4-80. One patient had more than 100 lesions.
Lesions are usually present on the trunk, buttocks, and upper and lower extremities. See the image below.
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Nearly perfectly round, slightly hyperkeratotic, hyperpigmented, asymptomatic plaque on the trunk.
Scrapings of pityriasis rotunda skin lesions can be examined using potassium hydroxide mount and sent for fungal culture to rule out tinea corporis and other dermatomycoses.[10] Examination with a Wood light is useful in cases suggestive of extraflexural erythrasma.
For pityriasis rotunda, use history and physical examination findings directed toward any underlying systemic diseases to guide further laboratory and imaging studies.
Consider investigations into the possibility of hepatocellular carcinoma in black South African patients with pityriasis rotunda.[42]
Histopathological features vary, but they primarily consist of hyperkeratosis and basal layer hyperpigmentation.[42] Hyperkeratosis may present as orthokeratotic or parakeratotic. Other findings may include plugs within hair follicles, a diminished or absent granular layer, pigmentary incontinence, mild spongiosis, elongated rete ridges, and lymphocytic perivascular infiltrate.[10] See the image below.
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Classic histology for pityriasis rotunda demonstrating mild hyperkeratosis and a reduced granular layer in the epidermis.
Improvement of pityriasis rotunda has been noted with 0.1% tretinoin cream, 10% lactic acid lotion, and 5% salicylic acid ointment; however, there is no effective local therapy and the pityriasis rotunda lesions usually are resistant to treatment.[42] Improvement with treatment of the underlying disease has also been noted. The condition is difficult to treat and current treatments are often poorly efficient, with resolution sometimes taking months or years.[10]
Clinical Context:
Tretinoin topical inhibits microcomedo formation and eliminates lesions. It makes keratinocytes in sebaceous follicles less adherent and easier to remove. It is available as 0.025%, 0.05%, and 0.1% creams and 0.01% and 0.025% gels.
Retinoids decrease the cohesiveness of abnormal hyperproliferative keratinocytes and may reduce the potential for malignant degeneration. They modulate keratinocyte differentiation. Retinoids have been shown to reduce the risk of skin cancer formation in renal transplant patients.
Clinical Context:
Ammonium lactate relieves itching and aids healing of skin in mild eczemas and dermatoses; itching skin, minor wounds, and minor skin irritations. Lactic acid is an alpha-hydroxy acid with keratolytic properties.
Emollients contain colloidal solids and various oils that act as emollients. They are recommended for relief of minor skin irritations and pruritus associated with common dermatoses and dry skin conditions.
Clinical Context:
By dissolving the intercellular cement substance, salicylic acid topical produces desquamation of the horny layer of skin while not affecting the structure of viable epidermis. Hydrate the skin and enhance the effects of the medication by soaking the affected area in warm water for 5 minutes prior to use. Remove any loose tissue with a brush, washcloth, or emery board and dry thoroughly. Improvement generally occurs in 1-2 weeks. Maximum resolution is expected after 4-6 weeks.
Jaggi Rao, MD, FRCPC, Clinical Professor of Medicine, Division of Dermatology and Cutaneous Sciences, Director of Dermatology Residency Program, University of Alberta Faculty of Medicine and Dentistry, Canada
Disclosure: Nothing to disclose.
Coauthor(s)
Kaushik P Venkatesh, George Washington University School of Business
Disclosure: Nothing to disclose.
Specialty Editors
Richard P Vinson, MD, Assistant Clinical Professor, Department of Dermatology, Texas Tech University Health Sciences Center, Paul L Foster School of Medicine; Consulting Staff, Mountain View Dermatology, PA
Disclosure: Nothing to disclose.
Chief Editor
Dirk M Elston, MD, Professor and Chairman, Department of Dermatology and Dermatologic Surgery, Medical University of South Carolina College of Medicine
Disclosure: Nothing to disclose.
Additional Contributors
Andrei I Metelitsa, MD, FRCPC, Assistant Clinical Professor, Section of Dermatology, University of Calgary Faculty of Medicine, Canada
Disclosure: Nothing to disclose.
Andrew Lin, MD, FRCPC, † Associate Professor, Department of Internal Medicine, Division of Dermatology, University of Alberta
Disclosure: Nothing to disclose.
James W Patterson, MD, Professor of Pathology and Dermatology, Director of Dermatopathology, University of Virginia Medical Center
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