Symptomatic uterine leiomyoma mimicking a myeloproliferative neoplasm with suspected red degeneration and secondary thrombocytosis post-caesarean section: a case report

Uterine leiomyomas are common benign tumours and may undergo red degeneration when their blood supply is compromised. Postpartum red degeneration is uncommon and can present with clinical and laboratory features that resemble infection or haematological disease. We describe a 35-year-old para 1 woman who presented four months after Caesarean section with lower abdominal pain, fever, night sweats, weight loss and generalised malaise. She had known large uterine leiomyomas. Blood tests showed microcytic anemia, raised inflammatory markers, a C-reactive protein concentration of 299 mg/l and marked thrombocytosis, with a peak platelet count of 1380 x 10^9/l. Pelvic magnetic resonance imaging demonstrated a large posterior uterine leiomyoma with features suggestive of acute red degeneration. Diffuse low T1 signal in the visualised pelvic bone marrow raised the possibility of an underlying marrow disorder. Following haematology, radiology and gynaecology review, the differential diagnosis included a severe reactive inflammatory response due to fibroid degeneration and a myeloproliferative neoplasm. The patient underwent laparotomy and myomectomy. Histopathological examination confirmed a benign leiomyoma with extensive red degeneration, infarction and acute-on-chronic inflammation. Her symptoms and inflammatory markers improved after surgery. This case illustrates that red degeneration of a postpartum leiomyoma may produce marked reactive haematological abnormalities and mimic a myeloproliferative disorder. Correlation of the clinical course with imaging, haematological assessment and histopathology was essential in establishing the diagnosis.