Differential Diagnosis

• Single most likely diagnosis
  • Hemophilia: The patient's family history of "bleeders" and the coagulation profile showing a prolonged partial thromboplastin time (PTT) with a normal prothrombin time (PT) and normal platelet count are indicative of Hemophilia A or B. Hemophilia A is a deficiency of factor VIII, while Hemophilia B is a deficiency of factor IX, both of which would lead to a prolonged PTT.
• Other Likely diagnoses
  • Von Willebrand Disease: This condition could also present with a prolonged bleeding time and prolonged PTT due to its effect on von Willebrand factor, which is crucial for platelet adhesion and also serves as a carrier for factor VIII. However, the normal platelet count and specific family history of "bleeders" make Hemophilia more likely.
• Do Not Miss
  • Disseminated Intravascular Coagulation (DIC): Although less likely given the normal PT and the specific pattern of coagulation abnormalities, DIC is a condition that can present with a variety of coagulation profile abnormalities, including prolonged PTT. It is crucial to consider DIC due to its high mortality rate if left untreated.
• Rare diagnoses
  • Factor XI deficiency: This is a rare bleeding disorder that could present with a prolonged PTT. However, it is less common than Hemophilia and often has a milder clinical presentation.
  • Factor XII deficiency: Similar to Factor XI deficiency, Factor XII deficiency can cause a prolonged PTT but is rare and usually asymptomatic.
  • Other rare factor deficiencies (e.g., factors II, V, VII, X): These deficiencies can affect PT, PTT, or both, but are less likely given the specific pattern of abnormalities and the clinical context provided.