Dear Editor, A 68-year-old man (case 1) presented with multiple 3-cm scalp nodules. A punch biopsy showed an infiltrate of pleomorphic medium to large size CD20+ve lymphoid cells, compatible with follicular large cell B-cell lymphoma (Fig. 1a). Bilateral marrow staging, complete blood counts, and whole body computerized tomography (CT) were negative. A remission was achieved with R-CEOPx 6 (rituximab, cyclophosphamide, epirubicin, vincristine, and prednisolone). Two years later, he developed polycythemia vera (Fig. 1b; PV: hemoglobin (Hb) 20.6 g/dl, white cell count (WCC) 8.3×10/l, platelet count (Plt): 758×10/l) with Jak2 V617F mutation detected in blood but not in the archival biopsy specimens [1]. He was put on hydroxyurea for 3 years when his 103-year-old father was noticed to have bilateral cervical lymphadenopathy and a monoclonal IgGλ paraprotein 16.7 g/l (case 2). An excision biopsy showed CD20+ve, CD10−ve lymphoplasmacytic lymphoma (Fig. 1c). Bilateral marrow staging and complete blood counts were normal and a CT scan showed no hepatosplenomegaly. He was treated with rituximab four times and chlorambucil (2 mg daily×3 months), with resolution of lymph nodes and monoclonal gammopathy. Three months later, however, he presented with persistent leukocytosis (Hb: 9.6 g/dl, WCC: 18.3×10/l, Plt: 93×10/l). A marrow biopsy showed markedly hypercellular particles with dysplastic megakaryocytes and ring sideroblasts (Fig. 1d) compatible with myeloproliferative disease (MPD-unclassified). Cytogenetic study, Jak2 mutation, and tumor marker screening were negative. Despite rising WCC, he remained asymptomatic (Hb: 8.6 g/dl,WCC 32.5×10/l, Plt: 62×10/l) but died of cerebrovascular accident 1 year from initial presentation. Four siblings and three offspring of case 1 had no evidence of lymphoma, Jak2 mutation, or hematological abnormality. To the best of our knowledge, this is the first familial occurrence of lymphoma followed by t-MPD. The genetic markers for familial lymphoma and familial MPD are both unknown. Similar to our cases, both entities show genetic anticipation [2, 3], and the individual lymphoma and MPD entities may be discordant [4]. Therapy-related MPD, PV, and CML after lymphoma treatment has occasionally been reported [5–7]. Although this may be a chance association, lymphoma patients may have genetic predisposition to MPD. Low levels of Jak2 mutation have been detected in lymphoma marrow specimens [8]. Patients with myeloid malignancies also have increased familial risk of lymphoma and vice versa [9]. Hence, a genetic link between familial lymphoma and familial MPD is also possible. It is interesting to note that with prolonged and detailed follow-up, more idiopathic MPD cases actually turn out to be familial in nature [3]. The recognition of these index families with distinct patterns of malignancies may be invaluable to future research on disease pathogenesis for both entities. Ann Hematol (2008) 87:931–932 DOI 10.1007/s00277-008-0503-y