The pityriasis rosea calendar: a 7 year review of seasonal variation, age and sex distribution.

BACKGROUND

The most accepted aetiologic factor for Pityriasis Rosea (PR) is viral infection and the evidences for this include the seasonal variation of the disease; intolerance to ampicillin; rarity of second attack; occasional household clustering of cases; and response to acyclovir in the early stage of the eruption.

OBJECTIVE

This is a review of the seasonal variation, age and sex distribution of patients who presented with Pityriasis Rosea at the dermatology outpatient clinic of the Lagos University Teaching Hospital (LUTH) between January 2000 and December 2006.

METHODS

Data was extracted from the clinic records and patients' records. The diagnosis of PR was made clinically based on the typical history, identification of the herald patch and characteristic 'Christmas tree' distribution of the exanthematic rash.

RESULTS

The diagnosis of Pityriasis Rosea was made in 427 patients (3.7%) of the 11,535 patients seen during the study period. The highest number of patients was seen in October (49 patients--11.5%); followed by August (48 patients--11.2%), March (46 patients--10.8%) and September (40 patients--9.4%). The least number of patients with PR were seen in January (21 patients--4.9%) and February (23 patients--5.4%). Pityriasis Rosea was seen predominantly in persons between the ages 10 and 29 (255 patients--59.7%) with a male to female ratio of 1: 1.55.

CONCLUSION

Pityriasis Rosea can be described as a disease of the rainy season found predominantly in the teenagers and young adults, with a female predilection.