PB1297 - Management of myh9-related platelet disorders (myh9‐rds) in a single center: focus on diagnosis and off-label therapy with tpo-mimetics.

Tuesday, June 25, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

MM

Maria Chiara Molinari

Hematologist, Medical Doctor
(1) Hematology, Department of Translational and Precision Medicine, Sapienza University, Rome, Italy.
ROMA, Lazio, Italy

Co-Author(s)

as

anna savoia

PhD
(2) Department of Engineering for Innovation Medicine, University of Verona, Verona, Italy
Verona, Veneto, Italy
mf

michela faleschini

biologist
(3) Department of Medical Genetics, Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy
trieste, Friuli-Venezia Giulia, Italy
EB

Erminia Baldacci

Hematologist, Medical Doctor
(1) Hematology, Department of Translational and Precision Medicine, Sapienza University, Rome, Italy
roma, Lazio, Italy
AT

Ambra Taglietti

Medical Doctor
(1) Hematology, Department of Translational and Precision Medicine, Sapienza University, Rome, Italy.
roma, Lazio, Italy
af

anna laura faccini

MD
(1) Hematology, Department of Translational and Precision Medicine, Sapienza University, Rome, Italy.
roma, Lazio, Italy
fp

francesca paoletti

MD
(1) Hematology, Department of Translational and Precision Medicine, Sapienza University, Rome, Italy.
roma, Lazio, Italy
ac

antonio chistolini

MD
(1) Hematology, Department of Translational and Precision Medicine, Sapienza University, Rome, Italy.
roma, Lazio, Italy
RM

Rosaria Mormile

Biologist
(1) Hematology, Department of Translational and precision Medicine, Sapienza University, Rome, Italy
Rome, Lazio, Italy
CS

Cristina Santoro

Hematologist, Medical Doctor
(1) Hematology, Department of Translational and Precision Medicine, Sapienza University, Rome, Italy
roma, Lazio, Italy

Background: MYH9-related platelet disorders (MYH9-RDs) are autosomal dominant syndromic thrombocytopenias caused by mutations in the MYH9 gene, which encodes for non-muscular myosin heavy chain IIA (NMMHC-IIA). MYH9-RDs may be associated with extrahematologic manifestations and Döhle-like bodies within leukocytes.

Aims: This study aims to establish a correct diagnostic process for MYH9-RD patients and demonstrate positive outcomes using off-label eltrombopag.

Methods: Six pts affected by MYH9-RD are followed in our Institute detailing their characteristics in Table 1.
Prior misdiagnosis of immune thrombocytopenia in 5/6 patients before arriving to our center. Four/6 underwent invasive diagnostic procedures such as bone marrow aspiration and biopsy. Three/6 patients were unsuccessfully treated with prednisone (0.5-1 mg/kg/day); two had been previously transfused with platelet concentrates and one received intravenous immunoglobulins. At our clinic, we suspected congenital thrombocytopenia. The venous blood smear showed giant platelets and the presence of Dohle-like bodies in the neutrophil’s cytoplasm (Fig.1). Upon genetic testing, mutations in the MYH9 gene were detected. Three/6 patients required treatment: 1 to undergo an ovarian cyst removal, 1 for repeated oocyte pick-up procedures, and the last one due to ulcerative colitis bleeding complications. We started off-label therapy with eltrombopag (TPO-mimetic) at a dosage of 50 mg/day. The baseline platelet levels were 39 x 10^9/L in two cases and 11 x 10^9/L in the other one. Within twenty days from therapy initiation, all 3 patients reached platelet values >90 x 10^9/L. Two patients underwent the procedures without complications, whereas the 3rd one experienced reduction and eventually halting of rectal bleeding.

Results: Giant platelets and Dohle-like bodies, along with minimal bleeding symptoms, indicated inherited thrombocytopenia. Effective eltrombopag treatment as needed.

Conclusion(s): Our cases emphasize considering inherited thrombocytopenias in diagnostics, avoiding unnecessary invasive procedures, and adopting effective treatments when necessary.