A child with factor V deficiency with a novel F5 gene mutation misdiagnosed as a left iliac fossa abscess: A case report.

Rationale: Congenital factor V deficiency is classified as a rare bleeding disorder that is expressed in an autosomal recessive manner and generally occurs in 1 in a million people. This disorder is accompanied by a variety of clinical manifestations, which can easily lead to misdiagnosis. This is the first report to identify the factor V gene variant c.2439delC (p.I814Lfs*23) in exon 13.

Patient concerns: A 13-year-old boy was admitted with a suspected left iliac fossa abscess. He had been previously diagnosed with and underwent management for a left iliac fossa abscess at a local hospital. The patient was treated with antibiotics and underwent surgical excision; however, his left iliac fossa mass reappeared. Platelet count and function, prothrombin time, and activated partial thromboplastin time were all normal.

Diagnoses: The patient was considered to have congenital factor V deficiency following the measurement of coagulation factor activity, and the diagnosis was confirmed by genetic testing.

Interventions: The mass was diagnosed as an abscess and the patient was treated with antibiotics at the local hospital. Surgical resection was performed, after which the mass was identified as a hematoma. The patient was then transferred to our hospital for treatment with fresh frozen plasma (FFP) infusion.

Outcomes: The left iliac fossa mass stopped growing and the coagulation function exhibited a significant improvement. At discharge, the patient was recommended to seek medical help before any surgical intervention or following trauma, and when a deep hemorrhage is identified, the patient should undergo timely infusion with FFP.

Lessons: This case report presents a rare occurrence of congenital factor V deficiency resulting in a left iliac fossa hematoma mistaken for an abscess, which resulted in unnecessary antibiotic therapy and surgery. This case emphasizes that coagulation factor deficiency should be highly suspected for joint mass combined with coagulation dysfunction.