Myositis
Eine 42 jährige Patientin mit seit Jahren bekannter Sarkoidose, welche auch unter fibromyalgiformen Schmerzen leidet, zeigt bei einer Laborkontrolle überraschend folgende blutchemischen Werte:
CRP normal, Blutbild unauffällig, CK 4236 U/L (Norm <192), GOT 55 U/L (<35), GPT 38 U/L (<35), LDH 272 U/L (<214).
Die Konstellation entspricht einer Muskelschädigung, dd einer autoimmunen Myositis, einer Sarkoidose-assoziierten Myopathie oder einer Nebenwirkung von Statinen. Ausser Methotrexat zur Behandlung der Sarkoidose nimmt die Patientin gelegentlich Prednison in Eigenregie, hat aber nie Statine erhalten.
Die Frage nach ergänzenden Substanzen führt schliesslich zu Vitachol, einem Präparat, welches Monascus purpureus enthält. Dieser Pilz wird auch im roten Reis gefunden. Er hat dieselbe Wirkung wie cholesterinsenkende Statine (e.g. Atorvastatin, Rosuvastatin). Selten kann der Monascus purpureus auch eine HMGCR Antikörper positive autoimmune nektrotisierende Myopathie auslösen.
Ein neuer Blog (HMGCR-positive Myopathie) fasst eine kürzliche Publikation (Dissertationsarbeit) über diese seltene und oft übersehene immun-bedingte Myopathie zusammen.
Barbara Williams, Michael P. Horn, Yara Banz, Laurence Feldmeyer, Peter M. Villiger
Abstract
Objective: Anti-3-Hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) positive immune-mediated necrotizing myopathy (IMNM) is a rare disease. It is induced by exogenous substances, most often by statins. Little is known about cutaneous manifestations of HMGCR positive IMNM and about HMGCR antibody positivity in other diseases.
Methods: The characteristics of patients with anti-HMGCR autoantibodies measured at our laboratory between January 2012 and September 2020 were studied. Characteristics of patients with IMNM were compared to those patients with positive antibodies but without muscle involvement. Associations of IMNM with other organ involvements were searched for.
Results: Of the 32 patients studied, 23 showed characteristics of IMNM, 9 did not fulfill current classification criteria but most showed signs of connective tissue diseases. Patients with IMNM were older (66 and 35 years, respectively; 0.92 (0.73–0.98); p < 0.001), had more frequent statin exposure (87% and 33%, respectively; 0.84 (0.61–0.94); p = 0.005) and higher mean peak CK (8717U/l and 329U/l, respectively; 1.0 (0.85–1.0); p < 0.001). 13/23 (56%) of IMNM patients showed cutaneous lesions; none of the patients suffered from cancer; only three IMNM patients showed drug-free complete remission. Incidence of IMNM in the catchment area of our center is at least 2.7/Mio/year.
Conclusion: Cutaneous lesions were found to be more frequent in anti-HMRCR positive IMNM than previously reported. Titer of anti-HMGCR antibodies and CK levels were significantly higher in IMNM than in other autoimmune connective tissue diseases. The data support the hypothesis of an antigen-driven response in IMNM, and suggests an activation of autoreactive B-lymphocytes in non-IMNM patients.