Sarcoidosis patients can be divided into women over age 40 with skin and eye lesions, and men under 40 with lung involvement, according to a large survey conducted in Japan.
The study, titled “Nationwide survey on the organ-specific prevalence and its interaction with sarcoidosis in Japan,” was published in the journal Scientific Reports.
Sarcoidosis is a highly heterogeneous inflammatory disease that can affect almost any organ in the body. Lungs are the most commonly affected, followed by lymph nodes, skin, and eyes. Sarcoidosis symptoms and severity vary widely among patients, making it difficult to diagnose.
Due to its heterogeneity, it is difficult to clarify sarcoidosis characteristics, including its prevalence and organ involvement in each gender and at different ages.
Researchers in Japan conducted a large nationwide survey to clarify the age- and gender-specific prevalence of lung, eye, and skin involvement in Japanese sarcoidosis patients.
They analyzed data of 9,965 newly diagnosed sarcoidosis patients who were registered into a database at the Ministry of Health, Labour and Welfare in Japan between 2002 and 2011.
The analysis focused on age at diagnosis, gender, and the involvement of the lungs, eyes, and skin. Lung lesions were classified based on the presence or absence of enlarged lymph nodes near the lungs — a condition called bilateral hilar lymphadenopathy (BHL) — or of nodules in the lungs, called diffuse lung shadow (DLS).
Among the analyzed patients, 6,333 were women (63.5%), 3,632 were men (36.5%), and their mean age at diagnosis was 54. While women were mostly diagnosed from ages 50 to 69, men were mostly diagnosed at two age groups: 30 to 39 and 60 to 69.
Most patients showed lung involvement (86.9%), followed by eye lesions (50.4%) and skin lesions (32%). BHL was reported in 78.6% of patients, while DLS was found in 45.4% of patients.
According to the researchers, the very high frequency of eye lesions observed in this analysis is consistent with the unique characteristics of sarcoidosis in Japanese patients.
The frequency of lung involvement at the time of diagnosis significantly decreased with age, while that of skin lesions was found to significantly increase with age.
Higher frequencies of eye lesions were found at ages 20-29 and 60-80 in women, and at 20-29 and 50-70 in men.
Women (most of whom were older than 40) showed a significantly higher prevalence of eye and skin lesions and a lower frequency of lung problems compared to men.
Lung involvement was significantly more frequent in men and was associated with a lower frequency of skin lesions.
In patients with eye lesions, the prevalence of BHL was significantly higher, whereas that of DLS was significantly lower. The team of researchers noted that the reason behind these associations is unknown, but they noted that genetic factors may be involved.
An additional analysis considering multiple factors showed two potential different profiles among sarcoidosis Japanese patients: women over 40 with skin and eye involvement, and men under 40 with lung involvement.
These findings may help to better understand the mechanisms behind the development of the disease in each organ, and “contribute to a better understanding of the heterogeneous features of sarcoidosis and the management of those with the disease,” the researchers wrote.
The Japanese team also noted that these results may not be generalized to other ethnic populations, and similar large-scale analyses in other parts of the world should be conducted.