SS is characterized by chronic, non pruritic recurrent  urticaria rash (pruritus is usually absent, especially at the disease onset. Lesions might become mildly pruritic in approx. 29% of patients after 3-4 years). The rash affects primarily the trunk and the extremities, sparing the palms, the soles and the head and neck areas. In some cases, it is triggered by ingestion of alcohol.

The urticarial rash consists of annular erythematous and macupapular pale-rose lesions of 0.5-3 cm diameter and sometimes confluent. Lesions last 12-36 hours and resolve completely, while new ones appear daily.

This first occurrence (it may not be followed by others for a long time) and other symptomatologic aspects help in defying the syndrome:

• Intermittent fever (in 90% of patients) Body temperature over 40 C . Each febrile episode usually resolves within a few hours; however, fevers can persist for up to 24-48 hours. In most cases, the fever and the skin rash are not related.

• Arthralgia  (in 60% of patients)

• Bone pain (in 50% of patients), mostly affects the iliac bone and the tibia. The femur, spin forearms and clavicle are less often involved.

• Myalgia

• Fatigue

• Weight loss

• Lymphadenopathy may be found in 50% of patients.

• Hepatomegaly (in 25% of patients)

• Splenomegaly (in 6.7% of patients)

But the syndrome is characterized by:

Monoclonal gammophaty (IgM detectable with serum immunoelectrophoreisis).

Hematological screening often enhances:

• Increase in  erythrocyte sedimentation rate (ESR)  (85% of cases)

• leucocystosis (60% of cases)

• thrombocytosis (20% of cases)

Radiological screening:

• Hyperostosis (increase in bone density, corresponding to the painful areas)

The syndrome takes the name of the French dermatologist, Dott. Schnitzler, who first described it in1972.

The diagnosis is based on the combination of clinical, biological and radiological aspects that help differentiating SS from other similar conditions.

Therefore the characteristics of the syndrome are:

• Urticarial rash

• Monoclonal gammopathy IgM.

It is the disease of “open areas” and a major risk for people who stay or work in rural areas, especially from sundown to sunset.

• Tourists

• Missionaries

• Volunteers of pace organizations

• Ornithologists

• Soldiers

To the above factors must be associated at least 2 of the above mentioned:

• Fever

• Arthralgia

• Bone pain

• Palpable lymph nodes

• Hepatomegaly and Splenomegaly

• Increase in ESR

• Leukocystosis

• thrombocytosis

• Hyperostosis

These classifying aspects are fundamental for the correct diagnosis, for other diseases may present overlapping symptoms, such as cutaneous eruptions, fever and articular pain and/or muscular: however there isn’t  monoclonal gammopathy IgM.

A few examples:

• Adults Still’s disease. The cutaneous eruption is however  evanescent while  in Schnitzler syndrome it recurs chronically.

• Systemic Lupus erythematosus (SLE).Instead of increase in white cells and platelets (SS) in SLE there is a less than normal number of white cells (leukopenia), neutrophils (neutropenia), platelets (thrombocytopenia) and antinuclear antibodies are present (not in SS). In both pathologies there is an increase in ESR

• Urticarial vasculitis. Very similar to SS because of the nonpruritic urticarial eruption and over 24 hours persistence. There are articular and muscular pain and fever, increase in ESR and white cells. However the biopsy of the skin enhances aspects such as fibrinoid necrosis of vessels and perivascular neutrophilic infiltrate, rarely, or never found in SS patients.

• Cryoglobulinemia. Symptoms appear in cold weather and ther is presence of cryiglobulins.

The exact pathogenesis of SS is unclear.

There isn’t a specific therapy.

Nonsteroidal anti-inflammatory drugs (NAIDs), corticosteroids immunosoppressive agents have been used with variable effects.

The IL-1 receptor antagonist Anakinra is today the treatment of choice.

The prognosis is related to the evolution because in 10-15% of patients lymphoplasmacytic malignancy developes more than 10-20 years after the first signs of the syndrome.