# A Case of Myosin Heavy Chain 9-Related Disorder Following Splenectomy Due to Misdiagnosis of Idiopathic Thrombocytopenic Purpura

## TL;DR

A patient was misdiagnosed with ITP and underwent splenectomy, but later found to have a rare MYH9-related disorder, which was successfully managed with eltrombopag.

## Contribution

Highlights eltrombopag's efficacy in managing MYH9-RD, especially post-splenectomy, and emphasizes the need for accurate diagnosis to avoid inappropriate treatments.

## Key findings

- Eltrombopag improved platelet counts and clinical outcomes in a post-splenectomy MYH9-RD patient.
- Misdiagnosis of MYH9-RD as ITP can lead to unnecessary splenectomy and ineffective treatments.
- Thrombopoietin receptor agonists show promise in inherited thrombocytopenias.

## Abstract

This case study reports a patient with Myosin Heavy Chain 9 (MYH9)-related disorder (MYH9-RD) which is characterized by congenital macrothrombocytopenia, Döhle-like bodies, sensorineural hearing loss, cataracts, and glomerulopathy. Often misdiagnosed as idiopathic thrombocytopenic purpura (ITP), MYH9-RD requires accurate identification to avoid inappropriate treatments like steroids, rituximab, or splenectomy. Platelet transfusions were traditionally the only therapeutic option, but thrombopoietin receptor agonists (TPO-RA), specifically eltrombopag, have shown success in MYH9-RD treatment.

The case report involves a 27-year-old male with chronic ITP post-splenectomy, revealing thrombocytopenia, mild anemia, giant platelets, kidney failure, and hearing loss. Genetic testing identified a c.287C>T; p.(Ser96Leu) variant associated with MYH9-RD. Eltrombopag treatment, initiated before the definitive diagnosis, exhibited clinical and laboratory success. The study discusses the evolving landscape of treatments for inherited thrombocytopenias, emphasizing eltrombopag's efficacy, especially post-splenectomy, and its potential application in short-term preparations for elective surgeries.

The study underscores the importance of timely MYH9-RD diagnosis, preventing misdiagnoses and inappropriate treatments. Eltrombopag stands out as a potential therapeutic option, offering effective platelet count management, especially post-splenectomy, with ongoing research exploring alternative TPO-RAs. As MYH9-RDs are rare, increased awareness among healthcare professionals is crucial to ensure accurate diagnoses and optimal patient care.