A 48-year-old patient was admitted to our tertiary Rheumatology center after composite aortic valve graft replacement had been performed the month before due to 70% stenosis of the aorta combined with an aortic valve insufficiency. The patient had developed 4 months prior to admission rapid signs of cardial decompensation. The pathohistological analysis of the resected tissue revealed aortitis with lympho-plasma cell rich infiltrations around vasa vasorum and lymphatic aggregates in the adventitia (Figure 1). In addition, there was a thickened vessel wall with slight fibredesorganisation and intramural lamelliform necrosis of the media with sparse neutrophilic granulocytes, lymphocytes and plasma cells (Figure 2). Immunohistochemical studies including stainings for CD68, IgG4 and CD138 did not provide additional information. Off note, there were no granulomas present. In light of these histopathological findings, infectious aortitis as well as localized idiopathic aortitis were considered by the pathologists, however, no information regarding an infection has been provided on request

by the treating clinicians.

Due to the clinical presentation and histological findings, manifestated TA had been suspected by the treating surgeons, and therefore immunosuppression with 20 mg prednisolone per day was initiated in addition to therapeutic anticoagulation, and the patient was admitted to our hospital for further evaluation.

On admission the patient presented in good general condition with no relevant findings in the physical examination. An elevated INR of 2, 3 due to anticoagulation was observed, and all other routine parameters were unremarkable. Vascular ultrasonography was performed of the A. carotis, A. axillaris and A. femoralis of both sides without any abnormal findings. In addition, multiple immune parameters (ANA, ANCA, RF, ACPA) as well as bacterial serologies (TPHA, Borreliaburgdorferi) were analyzed. Surprisingly, TPHA testing revealed a very high titer of 1:10240. Confirmatory tests were performed additionally demonstrating the presence of IgG and IgM specific for Treponapallidum at high titers. Together with the histological findings the final diagnosis of syphilitic aortitis could be established reflecting Syphilis at stage III [1] .

The drug of choice to treat syphilis stage III is Penicillin G that was initially administered as a bolus therapy of two mega penicillin G in 50 ml in 30 minutes. The following two weeks the patient was treated with a continous infusion of 50 mega Penicillin G. The reason for this treatment regimen was to secure a robust concentration of Penicillin G and to avoid repeated intramuscular injections due to concomitant therapeutic anticoagulation [2] [3] .

With regard to the inflammatory aspects observed macroscopically and the histological findings of an inflammatory aortitis the diagnosis of TA has been initially suspected and consequently immunosuppression was initiated [4] [5] . TA is a rare disease—the incidence observed in a study of North American patients was calculated at 2.6/million/year, and affects most commonly young women [6] [7] . Generally, this disease presents with an inflammation of the vasa vasorum of the adventitia in the acute phase. This leads to a lymphocytic infiltrate of the media and a thickening of the intima due to proliferation of fibroblasts and smooth muscle cells. The chronic phase of TA is characterized by the destruction of the elastic tissue, which leads to fibrosis and ultimately stenosis. In addition, manifestation of aneurysms might occur complicating the disease course [4] [6] [7] . Similar lesions can be observed in syphilitic aortitis with endarteritis obliterans and concomitant infiltration of plasma cells and vessel wall fibrosis challenging the diagnosis. However, a histological feature characteristic of syphilitic aortitis is necrosis of the media, which could be observed in our patient [4] [5] . In contrast to TA, which is a rare disease in Western Europe, the numbers of Syphilis cases in Germany are increasing. The patient numbers increased 2011 from 3033 infections to 3698 in the following year, which results in an incidence rate of 4.5/100.000/year [8] .

The histological report of our patient mentioned a remoulding of the elastic fibres, lymphocyte infiltration and necrosis of the media, whereas the immunohistochemistry was inconspicuous. Regardless of the histological findings supporting an infectious etiology over TA, our patient did not suffer from the typical symptoms of TA including weakening of the brachial artery pulses, claudication or fatigue. In addition, the age of our patient did not match very well with the predominant manifestation age.

In summary, rheumatologists should have a high level of vigilance to exclude syphilitic aortitis in patients with suspected TA presenting with atypical or inconsistent findings prior to the establishment of immunosuppressive therapy.

Syphilitic aortitis is an important differential diagnosis to TA and should be excluded in patients with suspected TA presenting with atypical findings.