Do infections provoke exacerbations and relapses of thrombotic thrombocytopenic purpura?

Several case reports have suggested an association between infections and thrombotic thrombocytopenic purpura (TTP). In Case 1, a 37-year-old female presented with TTP 6 times over 7 years, requiring 242 therapeutic plasma exchanges (TPE), for a per-course range of 4-57 TPE (median 48), and treatment durations of 4-241 days (median 71 days), largely on account of multiple exacerbations (range 0-3, median 3). Twelve of 17 (71%) of her presentations or exacerbations were associated with suspected infections, with confirmation in 9 episodes.

Deciphering polycythemia.

Most causes of an elevated hematocrit can be determined with a simple workup that includes a complete blood count and chest x-ray. However, measurement of red blood cell mass and plasma volume is required to differentiate primary, secondary, and combined polycythemia. Phlebotomy is customary for primary disease and some secondary cases in which the underlying cause cannot be removed.

Recent-onset myelodysplastic syndrome mimicking acute leukemia during infection.

A previously healthy 74-year-old patient without a prior history of hematological disease presented with an acute respiratory infection. Peripheral pancytopenia led us to perform a bone marrow biopsy, and the diagnosis of undifferentiated acute myelogenous leukemia (AML, 61% blasts) was made. Following antibiotic treatment and resolution of the infection, the blast count in the bone marrow fell to 2%, leaving a clinicopathologic picture consistent with myelodysplastic syndrome (MDS, French-American-British type refractory anemia), and the patient survived for a total of 16.