Case Presentation:
The patient is a 51‐year‐old man with history of IVDA and depression who presented with complaints of bilateral leg pain and swelling. He attributed his symptoms to cold weather during a snowstorm. A routine CBC showed his platelet count was more than 1 million/UL on an automated analyzer, whereas, 1 year prior to this admission, his platelet count was 168,000/UL. Creatinine was 1.1 mg/dL. Venous Doppler was negative for DVT. Examination of the peripheral blood smear, however, showed that the elevated platelet count was erroneous. Surprisingly, there was an amorphous faint blue‐gray substance that has led to the falsely elevated platelet reading on the automated analyzer. During his hospitalization, the patient started to develop worsening renal function. Further laboratory data revealed nonreactive HIV and negative hepatitis B serology, whereas hepatitis C and cryoglobulins were positive. Plasmapheresis and IV steroids were begun, with subsequent improvement in the patient's renal function and symptoms.
Discussion:
Pseudothrombocytosis is a rarely reported phenomenon sometimes seen in patients with cryoglobulinemia. When present in cryoglobulinemia, pseudothrombocytosis is caused by anomalous protein precipitates that are falsely counted as platelets on automated cell analyzers. This phenomenon is triggered by cold. When cryoglobulins precipitate, they form particles of various sizes ranging between 3 and 24 μm. Because automated blood counters assess cell populations by their dimensions, the smaller particles are erroneously counted as platelets and the larger ones as leukocytes. Generally, significant RBC changes have not been reported. An erroneous reading of platelets and/or leukocytes in the presence of cryoglobulinemia by a cell counter is not limited to older automated cell counters but can also be given by new ones. This phenomenon also seems to vary by temperature.
Conclusions:
Thrombocytosis or leukocytosis, unconfirmed by examination of a peripheral blood film and manual counts, should raise a suspicion of cryoglobulinemia. Such findings may be the first indication that would prompt workup for cryoglobulinemia. This case illustrates the importance for hospitalists to carefully review the smear and perform a manual count when encountered with abnormal hematologic results and thus avoid an unnecessary delay in diagnosis.
Author Disclosure:
T. S. Hamieh, none; K. Koduru, none; M. K. Saha, none; N. Abd Al‐noor, none; V. Dimov, none.