Contributed by Mihaela Avramut, MD, PhD and Raymond E. Felgar, MD, PhD
The patient is an 82-year-old man with a history of hypothyroidism and chronic prostatitis, diagnosed with moderate thrombocytopenia on routine complete blood counts. No hepatosplenomegaly or lymphadenopathy were observed. Three months later, thrombocytopenia persisted and a bone marrow biopsy was performed to evaluate for a primary marrow etiology. The following results were reported:
The peripheral blood smear (Fig. 1) showed slight anisocytosis and poikilocytosis, with occasional plasmacytoid lymphocytes and large granular lymphocytes. No pseudo - Pelger-Huet cells or circulating blasts were noted. Platelets were decreased in number, with rare large forms noted.
Bone marrow biopsy, particle sections, and aspirate smears were examined. The marrow was normocellular to mildly hypercellular for age (20-30 % cellular) (Fig. 2), with a myeloid/ erythroid ratio within normal limits (2.3:1). No metastatic tumor, lymphoid infiltrates or granulomas were noted. Erythroid maturation was complete, with only rare nuclear irregularities, involving less than 10% of this lineage (Fig. 4). Complete myeloid maturation to the neutrophil stage was present with no overt dysmyelopoiesis. Megakaryocytes were present in moderately increased numbers, with occasional clustering (Fig. 2 and 3). Megakaryocyte morphology included abnormal forms, with both hypolobated forms and hyperlobated forms.
Reticulin staining showed no overt fibrosis (not shown).
Flow cytometric immunophenotypic studies performed on bone marrow aspirate showed approximately 1% CD34-positive myeloblasts, 2% CD117-positive immature myeloid elements, and a population of probable erythroid elements were present. No abnormal T cell or monoclonal B cell population was demonstrated.
Cytogenetics evaluation of bone marrow demonstrated 5 of 20 metaphases with an abnormal karyotype as follows: 46,XY,del(20)(q11.2q13.3). A representative karyotype is illustrated in Fig. 5.
The other 15 metaphase spreads examined showed a normal male karyotype, 46, XY.