Caveats and truths in genetic, clinical, autoimmune and autoinflammatory issues in Blau syndrome and early onset sarcoidosis.

Blau syndrome (BS) and early onset sarcoidosis (EOS) are, respectively, the familial and sporadic forms of the pediatric granulomatous autoinflammatory disease, which belong to the group of monogenic autoinflammatory syndromes. Both of these conditions are caused by mutations in the NOD2 gene, which encodes the cytosolic NOD2 protein, one of the pivotal molecules in the regulation of innate immunity, primarily expressed in the antigen-presenting cells. Clinical onset of BS and EOS is usually in the first years of life with noncaseating epithelioid granulomas mainly affecting joints, skin, and uveal tract, variably associated with heterogeneous systemic features. The dividing line between autoinflammatory and autoimmune mechanisms is probably not so clear-cut, and the relationship existing between BS or EOS and autoimmune phenomena remains unclear. There is no established therapy for the management of BS and EOS, and the main treatment aim is to prevent ocular manifestations entailing the risk of potential blindness and to avoid joint deformities. Nonsteroidal anti-inflammatory drugs, corticosteroids and immunosuppressive drugs, such as methotrexate or azathioprine, may be helpful; when patients are unresponsive to the combination of corticosteroids and immunosuppressant agents, the tumor necrosis factor-α inhibitor infliximab should be considered. Data on anti-interleukin-1 inhibition with anakinra and canakinumab is still limited and further corroboration is required. The aim of this paper is to describe BS and EOS, focusing on their genetic, clinical, and therapeutic issues, with the ultimate goal of increasing clinicians' awareness of both of these rare but serious disorders.

Blau syndrome, clinical and genetic aspects.

Blau syndrome (BS) is a rare autosomal dominant, autoinflammatory syndrome characterized by the clinical triad of granulomatous recurrent uveitis, dermatitis and symmetric arthritis. The gene responsible for BS has been identified in the caspase recruitment domain gene CARD15/NOD2. In the majority of patients, the disease is characterized by early onset, usually before 3-4years of age. The manifestations at disease onset are usually represented by articular and cutaneous involvement signs, generally followed later by ocular manifestations which are often the most relevant morbidity of BS. In some cases the presence of fever is also observed; atypical cases of BS have been reported with cardiovascular, neurological, renal, intestinal and other organ involvement. The rarity and the variations in the severity and evolution of its expressions do not permit sufficient data about optimal treatment for patients with BS. The first step of therapy is represented by the use of corticosteroids and successively, in case of unsatisfactory response, by additional treatment with immunosuppressive agents. The results with biologic anti-cytokine agents, such as anti-TNFα and anti-IL1ß, are different, particularly with regard to ocular morbidity. Clinical and genetic aspects of the familial and the sporadic form of BS will be discussed and focused on. A description of a case study of an Italian family is also included.

Extranodal Rosai-Dorfman disease: involvement of eye, nose and trachea.

Rosai-Dorfman disease (RDD) is a rare non-neoplastic histiocytic proliferative disorder characterized by painless lymphadenopathy. Extranodal lesions frequently occur in the head and neck regions. We report the clinical and histological features of extranodal RDD in a 43-year-old man with a previously unreported combination of multiple gross anterior epibulbar nodules in the right eye, submucosal masses of nasal septum and trachea, and no lymphadenopathy during the 12-year follow-up. The patient underwent ophthalmological, otolaryngological and systemic evaluation; gallium 67 scintigraphy; bronchoscopy; ophthalmic ultrasound; head and neck CT scan; biopsies of epibulbar, nasal and tracheal tissues; and septoplasty. Histological specimens showed lymphocytophagocytosis and positive immunoperoxidase staining for S100 protein in foamy histiocytes; both features were typical for RDD. No response to topical or systemic steroids or to radiation therapy was recorded. Removal of nasal septum masses resolved nasal obstruction. The diagnosis of RDD requires histological and, in challenging cases, immunohistological specimens and is difficult--especially with pure extranodal localizations as in our case. RDD should be suspected in cases of subconjunctival mass and/or submucosal nasal and tracheal swellings not responding to systemic steroids.