Sarcoidosis is considered an inflammatory multi-system disease of unclear etiopathogenesis, which is histopathologically characterized by the generation of granulomas of epithelioid cells, including giant cells with no central necrosis within the connective tissue of the associated organs [1]. The prevalence of this disease is 40/100,000 inhabitants in Western Europe with an incidence of 10/100,000/year. The highest incidence rate is in the African-American part of the U.S. population as well as in Sweden and Iceland with a high number of estimated unknown cases overall [2]. Approximately 45–60% of cases were women [3]. Women typically got sick later in life (50–60 versus 30–50 years of age in men). In total, the incidence of the disease peaks at the age range of 40–55 years [2].

There were numerous environmental factors associated with the development of sarcoidosis, e.g., high mold burden, exposure to insecticides and silicates [4], [5]. Similarly, obesity is associated with sarcoidosis [6], [7]. Genetically, certain HLA-class-II alleles and further non-HLA-genes predispose for the disease. Apart from this, there are further, as yet incompletely determined genetic factors for familial accumulation. In the case of disease in the family, the risk of the illness increases in first-degree relatives by the factor 2-4. In several familial cases, the risk increases substantially [8].

The disease affects the lung or the mediastinum alone or in part in 83.6–91.7% of cases [9]. Even if manifestations in other organs are rather rare, sarcoidosis can affect each organ. The most frequently affected extrapulmonary organs are the skin, the eye and the liver. Manifestations in other organs, such as the endocrine system, occur very rarely [9], [10], [11]. There is in particular very little data available on sarcoidosis of the thyroid gland in the context of benign and malignant pathological lesions of the thyroid gland. A 2015 metaanalysis of data from more than 25,000 patients identified sarcoidosis as a significant risk factor for various tumor diseases [12].

Aim: Based on two representative cases who underwent surgical intervention for multinodular goiter and in whom histopathological investigation led incidentally to the discovery of an isolated extrapulmonary manifestation of a sarcoidosis of the thyroid gland, this rare diagnosis is to be described and further illustrated with regard to its occurrence and perioperative management reflecting daily clinical practice including scientific references and case-specific experiences on the clinical management as obtained.