Despite characteristics of aggressive lymphoma, very late-onset PTLDs after renal transplantation may respond to conventional chemotherapy. However, because a high rate of infectious complications occurred, new therapeutic strategies, such as combinations of anti-CD20 monoclonal antibodies and lower doses of chemotherapy, are warranted.

Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN) is a recently recognized highly aggressive malignant proliferation of plasmacytoid dendritic-cell (PDC) precursors which consistently express CD4, CD56 and CD123. Mortality is high despite transplant and the response to treatment is poor, except for preliminary results with conjugated anti-CD123. Clinically, cutaneous involvement is the most common feature with or without the presence of initial bone marrow infiltration, however patients may present with bone marrow-only disease. BPDCN is underdiagnosed, and can be confused with several entities, including acute myeloid leukemia. We describe our experience with 7 cases of BPDCN, their clinical and pathological presentation, and describe possible misdiagnosis and the antibodies that may help in corroborating BPDCN. See table for clinical characteristics at diagnosis. Diagnosis of BPDCN must take into account clinical, morphological and immunohistochemical analysis (IHC), since these tumors variably express markers that may be shared with other neoplasias including CD56 and TCL-1. When IHC is not categorical for BPDCN, the WHO recommends reporting the cases as AML of ambiguous lineage. The typical IHC includes CD4, CD43, CD45RA, CD56, CD123, TCL1, CLA and CD68. The absence of CD56 does not exclude the diagnosis. Markers shared with other hematological tumors include: CD7, CD33, CD2,CD36 and CD38 and TdT. Thus differential diagnosis should be done primarily with A) Skin infiltration by acute myeloid leukemia (myeloperoxidase +, 7- lysozyme +, CD34 +, CD117 +/-) B) Skin Infiltration by T / NK extra nodal lymphoma ( CD8 , cytotoxic cytoplasmic granules [CCG] , granzyme B, perforin, TIA1 and EBER) C) cutaneous peripheral T lymphoma ( +/- CD8, CD2 +/-, +/- CD5, CD7 +/- and variably positive CCG´s). D) Other histiocytic and dendritic cell-neoplasms may also be considered in the differential diagnosis however the histological appearance is usually characteristic. BPDCN is a poorly known entity that should be suspected by both clinician and pathologist in order to make a correct diagnosis. Table Table. Disclosures No relevant conflicts of interest to declare.

The aim of this study is to explore the expression of osteopontin (OPN) and its relationship with prognostic factors and survival in diffuse large B cell lymphoma (DLBCL). A tissue microarray was performed for immunohistochemical evaluation. Contingency tables were analyzed for trends; chi-square test was used to determine differences between groups. Univariate and multivariate Cox proportional hazards-regression analyses were performed to evaluate the impact of prognostic factors on survival. Expression of OPN was observed in 28%. It was different in non-germinal center DLBCL (P=0.04). The mean overall survival (OS) was lower in patients with positive OPN expression (19.762; CI 95% 14.269-25.255) it was not significant (P=0.123). It is not possible to establish a clear relationship between the expression by immunohistochemistry of osteopontin and a poor prognosis but it would be important to complement the analysis with other techniques as PCR or NGS that allow us to assess the influence of the isoforms and post-translational modifications of OPN on the biological behavior of DLBCL. Our findings indicate that OPN expression could be associated with a more aggressive variant of lymphoma: non-germinal center DLBCL.

BACKGROUND: Langerhans cell histiocytosis (LCH) is a rare condition in which granulomas form in tissues through the accumulation of abnormal histiocytes (Langerhans cells), granulocytes and lymphocytes. Prognosis in patients with disseminated disease has been associated with a chronic course, and a high morbidity and mortality rate. In terms of treatment, etoposide and vinblastine are considered to be the most effective agents in monochemotherapy. Here we report the case of an adult patient with LCH who has improved considerably after treatment with 2-CDA followed by IM. CLINICAL CASE: 37 year-old Hispanic female with history of burning epigastric pain, nausea and vomiting starting in 1998. In 1999 diarrhea and steatorrhea appeared. Whipple disease was diagnosed in another hospital but treatment was unsuccessful. She came to our hospital in 2003, complaining of the aforementioned symptoms plus severe malnutrition. Upper GI endoscopy and colonoscopy were performed and the biopsies showed infiltration with LCH. Bone marrow (BM) biopsy showed LCH infiltration too. CD117 (KIT) expression was investigated both in gastric and BM biopsies, turning out to be highly positive. Therapies and outcomes are shown in table 1. DATE DRUGS TREATMENT DURATION WEIGHT (Kg) ALBUMIN (g/dL) GI ENDOSCOPY BIOPSY Dec/03 VBL/VP-16/PDN 5 cycles 33.5 0.99 Polyps and pseudopolyps Infiltrated by LCH. Sep/05 MTX/PDN 18 mos. 39.5 3.18 Polyps and pseudopolyps Infiltrated. Jul/07 2-CDA 9 cycles 55.3 4.0 Polyps Infiltrated. May/08 IM 6 mos. 57 4.0 Nodular pattern. No polyps Decreased infiltration by LCH CONCLUSIONS: This case illustrates that multisystemic LCH can be successfully treated with, at least two more drug choices: 2-CDA and, in those patients with expression of KIT and/or PDGF, IM.