Rounds on pityriasis rotunda

By Warren R. Heymann, MD, FAAD
Aug. 7, 2024
Vol. 6, No. 32

Science, medicine, and patient strife aside, sometimes I just admire the beauty of skin lesions in and of themselves. Round, annular, and targetoid lesions (fixed drug eruptions, granuloma annulare, tinea, subacute lupus, erythema multiforme, erythema migrans, and others) are particularly appealing to me aesthetically. This commentary focuses on an entity that I have only rarely diagnosed yet may have profound implications — pityriasis rotunda (PR).

According to Sarkany and Hare: “Toyama was the first to describe this condition in 1906 in Tokyo and later (1913) he gave a detailed account of its clinical and aetiological features under the title tinea circinata. He described the geometrically perfect circular shape of the patches, but pointed out that rarely slightly oval shapes could be seen and that occasionally they could be confluent. Their size varied from 0.5-28 cm. in diameter, they were light or dark brown, scaly, well defined, 5-28 in number and they were situated mainly on the trunk and limbs. They were essentially symptomless but rarely there was slight itching. The very chronic course was punctuated by slight exacerbations and remissions. No causative agent was isolated. Attempts at experimental transfer of fresh scales from active patches to the normal skin of patients and to the skin of normal person with and without simultaneous scarification of the recipient area, were unsuccessful. While Toyama thought that there was probably no direct relationship of the disease to other affections, he pointed out that a high proportion of the patients had tuberculosis, dysentery or endometriosis. Independently, Matsura (1906) reported exactly similar cases under the heading pityriasis rotunda and Komorita (1907) helped further to clarify the clinical picture.” (1)

The original clinical description holds true. PR affects both genders, although there may be a slight female predominance. Most affected patients are 20 to 45 years old (ages 2 to 87). Most PR cases are reported in Japan and among West Indian and South African Blacks. Case reports of PR in black Americans are less common, it has rarely been reported in Caucasians. Lesions appear hyperpigmented in patients of color and are hypopigmented in those with light complexions. (2) Familial cases with an autosomal dominant transmission as demonstrated in a Sardinian family. (3) Most recently, in a Jordanian series of 23 PR cases, 3 were familial. (4) Interestingly, Guberman et al. reported PR in a brother and sister whose father had ichthyosis vulgaris. (5)

At most, lesions are mildly pruritic, as depicted in the case of a 19-year-old man reported by Li et al. (6) Surrounding skin may appear ichthyotic. (7) Dermatoscopic features demonstrate well-demarcated scales separated from each other by paler striae. (4) The differential diagnosis includes dermatophyte infections, tinea versicolor, erythrasma, pityriasis alba, pityriasis rosea, psoriasis, parapsoriasis, cutaneous T cell lymphoma, fixed drug eruption, and nummular eczema. (2) A KOH examination, fungal culture, and skin biopsy help differentiate these disorders – with an important exception — ichthyosis vulgaris — with both demonstrating hyperkeratosis, hypogranulosis, and potential follicular plugging. (4,5)

There have been many systemic associations reported with PR (malnutrition, diabetes, infections [tuberculosis, leprosy], cardiac disease, chronic obstructive pulmonary diseases, G6PD deficiency, scleroderma, sarcoidosis, hyperprolactinemia, others); however, most of which may be due to chance. (2) The most important consideration is that PR may be a paraneoplastic disorder, particularly with hepatocellular carcinoma. (8) Myeloproliferative diseases (chronic myelogenous leukemia, acute myeloid leukemia, and myeloma), and other malignancies (esophageal carcinoma, gastric carcinoma, and squamous cell carcinoma) have been reported. (2,8,9)

Grimalt et al proposed categorizing PR as type I (Black or Asian patients, non-familial, < 30 lesions, and associated in 30% of cases with malignancy or systemic disease) and type II (White patients, usually familial, > 30 lesions, and not associated with other diseases), while acknowledging that there are cases that do not fit this scheme. (3) Although the pathogenesis of PR is unknown, studies have demonstrated decreased filaggrin, filaggrin-2, and loricrin. (10) Acquired ichthyosis (AI) is a rare, nonhereditary cutaneous disorder that has been associated with numerous neoplastic, infectious, drugs, endocrine, metabolic, autoimmune, and malabsorptive diseases. The cutaneous changes in AI are clinically and histologically identical to those of ichthyosis vulgaris. (11) As previously mentioned, PR and ichthyosis vulgaris are microscopically indistinguishable. Conceptually, it is reasonable to approach most patients with PR as having acquired ichthyosis (especially those considered type I by the Grimalt et al. classification).

Therapeutically, treatment of the underlying disorder (especially malignancies) leads to the resolution of PR. The usual dermatological armamentarium (keratolytics [salicylic acid, lactic acid], topical steroids, retinoids, vitamin D analogs, tars) offer minimal benefit. (2)

In conclusion, PR is a quizzical disorder that may be considered an acquired ichthyosis in non-familial cases. In this context, clinicians should consider the possibility that it is a paraneoplastic process and not dawdle in getting round to an appropriate assessment.

Point to Remember: Pityriasis rotunda is a striking dermatosis with many reported associations, most notably as a paraneoplastic process in some cases.

Our expert’s viewpoint

Lorraine L. Rosamilia, MD, FAAD

Paraneoplasia holds a special place in a dermatologist’s psyche. Using the skin and our astute diagnostic skills as the proverbial window into the inner workings of a systemic disease or malignancy, we play a role in facilitating workups that would have otherwise been delayed or omitted. Whether it is part of a cutaneous cancer screening or a chief complaint of a new eruption or lesion, we have the opportunity to enhance multidisciplinary care and personify the SkinSerious role for better patient outcomes.

Pityriasis rotunda may not be on the tip of every dermatologist’s tongue or a shortcut on their EMR diagnosis list, but acknowledging that annular plaques with ichthyotic features in darker skin types could be a paraneoplastic sign earmarks it for our special attention.

1. Sarkany I, Hare PJ. Pityriasis rotunda. (Pityriasis circinata). Br J Dermatol. 1964 May;76:223-8. doi: 10.1111/j.1365-2133.1964.tb14514.x. PMID: 14155119.

2. Riley CA, Badri T, Hafsi W. Pityriasis Rotunda. 2022 Sep 12. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan–. PMID: 29083817.

3. Grimalt R, Gelmetti C, Brusasco A, Tadini G, Caputo R. Pityriasis rotunda: report of a familial occurrence and review of the literature. J Am Acad Dermatol. 1994 Nov;31(5 Pt 2):866-71. doi: 10.1016/s0190-9622(94)70248-9. PMID: 7962738.

4. Al-Refu K, Al-Tarawneh A, Odeibat H. Pityriasis rotunda. A clinical study in Jordan: experience of 10 years. Int J Dermatol. 2018 Jul;57(7):759-762. doi: 10.1111/ijd.13994. Epub 2018 May 17. PMID: 29774541.

5. Guberman D, Lichtenstein DA, Gilead L, Vardy DA, Klaus SN. Familial pityriasis rotunda. Acta Derm Venereol. 1997 Mar;77(2):162. doi: 10.2340/0001555577162. PMID: 9111837.

6. Li G, Xu Z, Huang L, Xue R. Pityriasis rotunda. Int J Dermatol. 2023 Aug;62(8):1098-1100. doi: 10.1111/ijd.16369. Epub 2022 Aug 7. PMID: 35933687.

7. Kahana M, Levy A, Ronnen M, Schewach-Millet M, Stempler D. Pityriasis rotunda in a white patient. Report of the second case and review of the literature. J Am Acad Dermatol. 1986 Aug;15(2 Pt 2):362-5. PMID: 3734184.

8. Chamli A, Kouki C, Belhadj O, Helal I, Hammami H, Fenniche S, Zaouak A. Pityriasis rotunda associated with hepatocellular carcinoma. J Eur Acad Dermatol Venereol. 2023 Jul 17. doi: 10.1111/jdv.19353. Epub ahead of print. PMID: 37458682.

9. Suzuki Y, Aoshima M, Fujiyama T, Ito T, Tokura Y. Pityriasis rotunda associated with acute myeloid leukemia. J Dermatol. 2018 Jan;45(1):105-106. doi: 10.1111/1346-8138.13802. Epub 2017 Mar 29. PMID: 28370261.

10. Makino T, Mizawa M, Seki Y, Hayashi M, Shimizu T. Decreased filaggrin-2 expression in the epidermis in a case of pityriasis rotunda. Clin Exp Dermatol. 2016 Mar;41(2):215-7. doi: 10.1111/ced.12716. Epub 2015 Jul 20. PMID: 26189536.

11. Haber R, Feghali J, Nadir U, Yi MD, Cahn BA. Acquired ichthyosis: a clinical review. Arch Dermatol Res. 2023 Jul 9. doi: 10.1007/s00403-023-02668-5. Epub ahead of print. PMID: 37422878.

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