Immune Thrombocytopenic Purpura (ITP): This condition is characterized by low platelet count due to immune-mediated destruction. The presence of fever could be due to an underlying infection or inflammation. Low hemoglobin could be secondary to bleeding or another underlying condition. The normal bone marrow biopsy supports this diagnosis as ITP typically shows a normal or increased number of megakaryocytes.

Viral Infections (e.g., HIV, Hepatitis C): Certain viral infections can cause thrombocytopenia and anemia. The fever could be a manifestation of the viral infection itself. Normal WBC count and procalcitonin levels do not rule out viral infections.
Drug-Induced Thrombocytopenia and Anemia: Various medications can cause thrombocytopenia and anemia. The fever could be related to the underlying condition for which the medication was prescribed or a drug reaction.
Chronic Diseases (e.g., Chronic Kidney Disease, Liver Disease): These conditions can lead to thrombocytopenia and anemia due to various mechanisms, including decreased production of erythropoietin and thrombopoietin, and the fever could be due to associated infections or inflammation.

Severe Sepsis or Septic Shock: Although the procalcitonin is normal, which argues against bacterial sepsis, it's crucial not to miss sepsis due to other pathogens (viral, fungal) or atypical bacteria. Sepsis can cause thrombocytopenia, anemia, and fever.
Hemophagocytic Lymphohistiocytosis (HLH): This is a life-threatening condition characterized by excessive immune activation, which can present with fever, cytopenias (including thrombocytopenia and anemia), and normal or elevated WBC count. A normal bone marrow biopsy does not rule out HLH, as the diagnosis often requires specific testing (e.g., soluble CD25, ferritin levels).
Thrombotic Thrombocytopenic Purpura (TTP): Although less common, TTP is a critical diagnosis to consider due to its high mortality if untreated. It presents with thrombocytopenia, microangiopathic hemolytic anemia (which could explain low hemoglobin), fever, renal failure, and neurological symptoms.

Paroxysmal Nocturnal Hemoglobinuria (PNH): A rare, acquired, life-threatening disease of the blood characterized by the destruction of red blood cells (hemolysis), bone marrow failure, and the potential for blood clot formation (thrombosis). Fever can be present due to hemolysis or associated infections.
Myelodysplastic Syndromes (MDS): Although the bone marrow biopsy is reported as normal, early or certain types of MDS might not show typical dysplastic changes. MDS can cause cytopenias, including anemia and thrombocytopenia, and fever could be due to associated infections or inflammation.
Lymphoma: Certain types of lymphoma can present with cytopenias due to bone marrow involvement and fever (as part of B symptoms). However, a normal bone marrow biopsy makes this less likely, though not impossible, especially if the biopsy sample did not capture involved areas.