Acquired Pelger-Huët anomaly in association with concomitant tacrolimus and fluconazole therapy following allogeneic bone marrow transplantation

Drug-drug interactions in patients receiving hematopoietic stem cell transplantation

INTRODUCTION

Recipients of hematopoietic stem cell transplantation (HSCT) are exposed to numerous drugs in both pre- and post-transplantation period, which creates an opportunity for drug-drug interactions (DDIs); if clinically relevant DDIs happen, the risk of adverse treatment outcomes is increased. Areas covered: This review is focused on DDIs in recipients of HSCT that were observed and published as clinical trials, case series or case reports. Relevant publications were found by the systematic search of the following online databases: MEDLINE, SCOPUS, EBSCO, and SCINDEX. Expert opinion: The most important DDIs involve cytostatic or immunosuppressant drug on one side, and antimicrobial drugs on the other. The majority of clinically relevant interactions have pharmacokinetic character, involving drug metabolizing enzymes in the liver. Antifungal azoles inhibit metabolism of many cytostatic and immunosuppressant drugs at cytochromes and increase their plasma concentrations. Macrolide antibiotics and fluoroqunolones should be avoided in HSCT recipients, as they have much larger potential for DDIs than other antibiotic groups. HSCT recipients increasingly receive new immunomodulating drugs, and further observational studies are needed to reveal unsuspected DDIs with clinical relevance.

Pelger-Huët anomaly in two related mixed-breed dogs

A 6-month-old male mixed-breed dog weighing 12.6 kg weight was presented for evaluation of a subcutaneous nodule on the dorsum. The medical history indicated trimethoprim-sulfamethoxazole treatment 2 months before presentation at the veterinary hospital. The initial complete blood cell count (CBC) results included an apparent left shift. Microscopic examination of a blood smear (Panoptic stain) revealed granulocytes with hyposegmented nuclei, coarse mature chromatin, and a nuclear shape varying from round to bilobed (pince-nez) or slightly indented. Occasional neutrophils and eosinophils had typical segmentation of nuclei. Abnormalities were not present in limited serum biochemical testing. The CBC was repeated 17 and 120 days later, and the results were similar to those observed in the first examination. The parents of the patient were located, and a CBC was performed on both animals. The dam, but not the sire, had nuclear hyposegmentation of granulocytes, confirming the diagnosis of Pelger-Huët anomaly.

Pseudo-Pelger-Huët anomaly induced by medications: a clinicopathologic study in comparison with myelodysplastic syndrome-related pseudo-Pelger-Huët anomaly

Pseudo-Pelger-Huët anomaly (PPHA) has been documented in association with transplant medications and other drugs. This iatrogenic neutrophilic dysplasia is reversible with cessation or adjustment of medications but is frequently confused with myelodysplastic syndrome (MDS) based on the conventional concept that PPHA is a marker for dysplasia. We investigated the clinicopathologic features in iatrogenic PPHA and compared them with MDS-related PPHA. The 13 cases studied included 5 bone marrow/stem cell transplantations, 3 solid organ transplantations, 1 autoimmune disease, 3 chronic lymphocytic leukemias, and 1 breast carcinoma. For 12 cases, there was follow-up evaluation, and all demonstrated at least transient normalization of neutrophilic segmentation. All 9 cases of MDS demonstrated at least 2 of the following pathologic abnormalities on bone marrow biopsy: hypercellularity (8/9), morphologic dysplasia (8/9), clonal cytogenetic abnormality (7/9), and increased blasts (3/9), whereas these abnormalities were typically absent in iatrogenic PPHA. Iatrogenic PPHA displayed a higher proportion of circulating PPHA cells than in MDS (mean, 47.4%; SD, 31.6% vs mean, 12.3%; SD, 9.8; P < .01). A diagnostic algorithm is proposed in which isolated PPHA is indicative of transient or benign PPHA unless proven otherwise.

Hematologic abnormalities following renal transplantation

Recipients of renal allografts are surviving longer and, consequently, may experience a variety of complications related not only to the transplanted kidney, but also to the hematopoietic system. Common hematologic complications in the renal transplant patient include abnormalities of one cell line, such as post-transplantation erythrocytosis or anemia, that are often treatable with simple measures. Conversely, pathologies involving the leukocyte and platelet population often exist in the context of pancytopenia, which may be a manifestation of systemic infection (e.g., cytomegalovirus, human herpesvirus 8) or malignancy (post-transplantation lymphoproliferative disorders). Uncommon, but life-threatening, processes complicating renal transplantation include hepatosplenic gammadelta T-cell lymphoma and viral-induced hemophagocytic syndrome, both of which are associated with severe pancytopenia and, often, death. Since this patient population is often managed in a multidisciplinary fashion by nephrologists, infection specialists, transplant surgeons, hematologists, and internal medicine physicians, a succinct review of this topic is warranted.

Pseudo-Pelger-Huët in kidney-transplanted patients

Pelger-Huët anomaly is an inherited condition characterized by hyposegmentation of the neutrophil nucleus and excessive chromatin clumping. Acquired Pelger-Huët, also known as pseudo-Pelger-Huët, has been described in several clinical conditions including transplant recipients who received immunosuppressive drugs. The incidence of pseudo-Pelger-Huët in kidney transplant patients, characterized as neutrophil dysplasia, was observed in 9 of 170 patients (5.3%) at the São Francisco Hospital de Assis, Belo Horizonte, Brazil. Awareness of possible circulating neutrophil alterations in transplant patients is important for laboratory professionals who should report these findings of cell changes. It should be highlighted that the poor segmentation and the chromatin hypercondensation observed initially in pseudo-Pelger-Huët patients can be suggestive of early-stage neutrophils. Only a combination of laboratory and clinical data will facilitate a better understanding of this anomaly and its correct follow-up and management.

Acquired Pelger-Huët anomaly in association with concomitant tacrolimus and mycophenolate mofetil in a liver transplant patient: a case report and review of the literature

Pelger-Huët anomaly is a congenital or acquired abnormality of neutrophil nuclear segmentation. The acquired form may be a result of a clonal myeloid malignancy, such as myelodysplastic syndrome, or may be a secondary nonclonal change related to a variety of underlying causes, including infections and medications. We report a case of a 56-year-old man who developed acquired Pelger-Huët anomaly following liver transplantation while on the immunosuppressive agents tacrolimus and mycophenolate mofetil. These medications have been reported in association with this abnormality, but usually as a single agent or in combination with other drugs. In our case, the Pelger-Huët anomaly may be the result of the combination of these 2 drugs or mycophenolate alone with subsequent desensitization because resolution of the abnormality occurred after a reduction in mycophenolate mofetil dose, and the abnormality did not recur when mycophenolate mofetil was increased to a dose previously associated with Pelger-Huët anomaly during the time that tacrolimus was discontinued.

Frequency of potential azole drug-drug interactions and consequences of potential fluconazole drug interactions

PURPOSE

To assess the frequency of potential azole-drug interactions and consequences of interactions between fluconazole and other drugs in routine inpatient care.

METHODS

We performed a retrospective cohort study of hospitalized patients treated for systemic fungal infections with an oral or intravenous azole medication between July 1997 and June 2001 in a tertiary care hospital. We recorded the concomitant use of medications known to interact with azole antifungals and measured the frequency of potential azole drug interactions, which we considered to be present when both drugs were given together. We then performed a chart review on a random sample of admissions in which patients were exposed to a potential moderate or major drug interaction with fluconazole. The list of azole-interacting medications and the severity of interaction were derived from the DRUGDEX System and Drug Interaction Facts.

RESULTS

Among the 4,185 admissions in which azole agents (fluconazole, itraconazole or ketoconazole) were given, 2,941 (70.3%) admissions experienced potential azole-drug interactions, which included 2,716 (92.3%) admissions experiencing potential fluconazole interactions. The most frequent interactions with potential moderate to major severity were co-administration of fluconazole with prednisone (25.3%), midazolam (17.5%), warfarin (14.7%), methylprednisolone (14.1%), cyclosporine (10.7%) and nifedipine (10.1%). Charts were reviewed for 199 admissions in which patients were exposed to potential fluconazole drug interactions. While four adverse drug events (ADEs) caused by fluconazole were found, none was felt to be caused by a drug-drug interaction (DDI), although in one instance fluconazole may have contributed.

CONCLUSIONS

Potential fluconazole drug interactions were very frequent among hospitalized patients on systemic azole antifungal therapy, but they had few apparent clinical consequences.

Hematologic toxicity of immunosuppressive treatment

The administration of immunosuppressive agents may be associated with the occurrence of hematologic toxicity, such as anemia, due to bone marrow suppression or hemolysis, leukopenia, and thrombocytopenia. The administration of azathioprine and mycophenolate mofetil is more frequently associated with bone marrow suppression, while hemolytic-uremic syndrome may occur after administration of cyclosporine, tacrolimus, or muromonab (OKT3) and may be associated with the loss of the allograft. Moreover, microangiopathic hemolytic anemia and thrombocytopenia are rare, but potentially severe, complications of immunosuppressive treatment with tacrolimus and cyclosporine; they are characterized by intravascular hemolysis due to mechanical destruction of red cells as a result of pathological changes in small blood vessels. Viral infections (cytomegalovirus), administration of antiviral agents (gancyclovir), inhibitors of angiotensin-converting enzyme and angiotensin II receptor antagonists, antibacterial agents (sulfamethoxazole and trimethoprim), and allopurinol may aggravate bone marrow suppression, particularly when administered with agents that interfere with purine biosynthesis, including azathioprine and mycophenolate mofetil.

Acquired and reversible Pelger-Huët anomaly of polymorphonuclear neutrophils in three transplant patients receiving mycophenolate mofetil therapy

Deficient nuclear segmentation and abnormal chromatin condensation define Pelger-Huët anomaly of polymorphonuclear neutrophils. Next to the hereditary irreversible form, acquired forms both reversible and irreversible have been described. We describe three transplant patients who were all investigated for a left shift in the absence of symptoms or signs of infection and in whom acquired reversible Pelger-Huët anomaly was discovered. The abnormal PMN phenotype was induced by mycophenolate mofetil (MMF). MMF is a necessary but not sufficient condition for the development of the anomaly. In our three patients a dose-response effect was observed regarding plasma MMF concentration and severity of neutrophil dysplasia. Except for one slightly elevated value, the patients' plasma MMF levels were within the therapeutic range. None of the patients, one who was neutropenic at presentation and two who were non-neutropenic, developed infectious complications. From our three cases as well as those of other authors, we identify previous graft rejection episodes as a potential predisposing factor for the development of PHA. In the first patient, drug withdrawal led to normalization of PMN morphology. In the other two patients, the left shift disappeared after dose reduction. In these latter two patients, a form of desensitization to the effect of MMF on neutro- phils was observed following re-augmentation of MMF dose.