What Are the Effects of Irreversible Electroporation on a Staphylococcus aureus Rabbit Model of Osteomyelitis?

BACKGROUND: The treatment of osteomyelitis can be challenging because of poor antibiotic penetration into the infected bone and toxicities associated with prolonged antibiotic regimens to control infection. Irreversible electroporation (IRE), a percutaneous image-guided ablation technology in which the targeted delivery of high-voltage electrical pulses permanently damages the cell membrane, has been shown to effectively control bacterial growth in various settings. However, IRE for the management of bone infections has yet to be evaluated. QUESTIONS/PURPOSES: We aimed to evaluate IRE for treating osteomyelitis by assessing (1) the efficacy of IRE to suppress the in vitro growth of a clinical isolate of S. aureus, alone or combined with cefazolin; and (2) the effects of IRE on the in vivo treatment of a rabbit model of osteomyelitis. METHODS: S. aureus strain UAMS-1 expanded in vitro to the log phase was subjected to an electric field of 2700 V/cm, which was delivered in increasing numbers of pulses. Immediately after electroporation, bacteria were plated on agar plates with or without cefazolin. The number of colony-forming units (CFUs) was scored the following day. ANOVA tests were used to analyze in vitro data. In a rabbit osteomyelitis model, we inoculated the same bacterial strain into the radius of adult male New Zealand White rabbits. Three weeks after inoculation, all animals (n = 32) underwent irrigation and débridement, as well as wound culture of the infected forelimb. Then, they were randomly assigned to one of four treatment groups (n = eight per group): untreated control, cefazolin only, IRE only, or combined IRE + cefazolin. Serial radiography was performed to assess disease progression using a semiquantitative grading scale. Bone and soft-tissue specimens from the infected and contralateral forelimbs were collected at 4 weeks after treatment for bacterial isolation and histologic assessment using a semiquantitative scale. RESULTS: The in vitro growth of S. aureus UAMS-1 was impaired by IRE in a pulse-dependent fashion; the number of CFUs/mL was different among seven pulse levels, namely 0, 10, 30, 60, 90, 120, and 150 pulses. With the number of CFUs/mL observed in untreated controls set as 100%, 10 pulses rendered a median of 50.2% (range 47.1% to 58.2%), 30 pulses rendered a median of 2.7% (range 2.5% to 2.8%), 60 pulses rendered a median of 0.014% (range 0.012% to 0.015%), 90 pulses rendered a median of 0.004% (range 0.002% to 0.004%), 120 pulses rendered a median of 0.001% (range 0.001% to 0.001%), and 150 pulses rendered a median of 0.001% (range 0.000% to 0.001%) (Kruskal-Wallis test: p = 0.003). There was an interaction between the effect of the number of pulses and the concentration of cefazolin (two-way ANOVA: F [8, 30] = 17.24; p < 0.001), indicating that combining IRE with cefazolin is more effective than either treatment alone at suppressing the growth of S. aureus UAMS-1. Likewise, the clinical response in the rabbit model (the percentage of animals without detectable residual bacteria in the bone and surrounding soft tissue after treatment) was better in the combination group than in the other groups: control, 12.5% (one of eight animals); IRE only, 12.5% (one of eight animals); cefazolin only, 25% (two of eight animals); and IRE + cefazolin, 75% (six of eight animals) (two-sided Fisher's exact test: p = 0.030). CONCLUSIONS: IRE effectively suppressed the growth of S. aureus UAMS-1 and enhanced the antibacterial effect of cefazolin in in vitro studies. When translated to a rabbit osteomyelitis model, the addition of IRE to conventional parenteral antibiotic treatment produced the strongest response, which supports the in vitro findings. CLINICAL RELEVANCE: Our results show that IRE may improve the results of standard parenteral antibiotic treatment, thus setting the stage for models with larger animals and perhaps trials in humans for validation.

Marginal zone variant of mantle cell lymphoma: CD5-negative cyclin D1-positive variant posing a diagnostic dilemma.

Described herein is an unusual case of mantle cell lymphoma (MCL) histologically mimicking marginal zone lymphoma (MZL). An 83-year-old man presented with multiple adenopathies and a hilar mass encroaching on the right lung. A transbronchial biopsy showed small blue cells suspicious for small cell carcinoma. On further analysis the cells were predominantly small cleaved and CD20 positive, suggesting follicular lymphoma, grade 2. An axillary lymph node biopsy showed germinal centers surrounded by monocytoid B cells. Flow cytometry was negative for CD5 and CD23 and the diagnosis of MZL was considered. Because of the aggressive clinical behavior, including extensive necrosis on imaging studies, immunohistochemistry for cyclin D-1 was performed and was positive. Bone marrow was extensively involved and it showed t(11;14), in addition to other complex cytogenetic abnormalities. Differentiating MCL from MZL has prognostic and therapeutic implications, particularly when considering the potential role of targeted therapy and cell cycle modulators.

A 32-Year-Old Man With HIV Infection, Pleural Effusions, and Lymphadenopathy.

CASE PRESENTATION: A 32-year-old man presented with fever, nonproductive cough, diffuse lymphadenopathy, and polyarticular pain for 2 weeks. His medical history included HIV diagnosed 10 years ago, anal intraepithelial neoplasia, Kaposi sarcoma, and herpes simplex virus-2 infection. The patient was not receiving antiretroviral therapy or antibiotic prophylaxis, and his last known CD4 count a month before was 45 cells/mm3. He was prescribed a course of doxycycline by his primary care physician, which did not improve his symptoms.

Effects of the Use of a Mallet during Bone Marrow Biopsy Collection on Specimen Quality: A Quality Improvement Project.

CONTEXT: Avoiding procedure-related morphologic distortion such as fragmentation and crush artifact is critical in bone marrow diagnosis. Use of a hammer or mallet, although infrequent, is a known technique of advancing the biopsy needle during specimen collection. OBJECTIVES: We performed a double-blinded, retrospective review of bone marrow biopsies collected by the Interventional Radiology department at our institution in order to assess specimen quality by using this technique. DESIGN: We reviewed 93 bone marrow biopsy specimens collected at our hospitals, between January 2015 and June 2015. Routine bone marrow core biopsy slides were reviewed. The presence of crush artifact, specimen fragmentation, and aspiration artifact, as well as the presence of osteopenia and an overall grade of specimen adequacy, was recorded for each specimen. RESULTS: A sterile mallet was used during the bone marrow biopsy procedure in 29 cases. Use of a mallet was significantly associated with the presence of suboptimal or inadequate specimen quality of bone marrow core biopsy (p<0.005) and was independently associated with severe specimen fragmentation (2+) (p<0.0001). There was no statistically significant association between length of the core and use of a mallet. CONCLUSIONS: Use of a mallet during bone marrow core biopsy collection is significantly associated with morphologic distortion in the form of severe specimen fragmentation and negatively affects specimen adequacy. There is no difference in length of core biopsy as previously thought by using a mallet to advance the needle during the procedure. We recommend that the use of this technique should be avoided during specimen collection.

Placenta Percreta in First Trimester after Multiple Rounds of Failed Medical Management for a Missed Abortion.

BACKGROUND: The detection of a morbidly adherent placenta (MAP) in the first trimester is rare. Risk factors such as multiparity, advanced maternal age, prior cesarean delivery, prior myomectomy, placenta previa, or previous uterine evacuation place patients at a higher risk for having abnormal placental implantation. If these patients have a first trimester missed abortion and fail medical management, it is important that providers have a heightened suspicion for a MAP. CASE: A 24-year-old G4P3003 with 3 prior cesarean deliveries underwent multiple rounds of failed medical management for a missed abortion. She had a dilation and curettage that was complicated by a significant hemorrhage and ultimately required an urgent hysterectomy. CONCLUSION: When patients fail medical management for a missed abortion, providers need to assess the patient's risk factors for a MAP. If risk factors are present, a series of specific evaluations should be triggered to rule out a MAP and help further guide management. Early diagnosis of a MAP allows providers to coordinate a multidisciplinary treatment approach and thoroughly counsel patients. Ensuring adequate resources and personnel at a tertiary hospital is essential to provide the highest quality of care and improve outcomes.

Burkitt lymphoma presenting as a mass in the thyroid gland: a clinicopathologic study of 7 cases and review of the literature.

Burkitt lymphoma presenting in the thyroid gland is rare, and only a few cases have been reported. We retrospectively reviewed 7 patients diagnosed with Burkitt lymphoma of the thyroid gland between 2000 and 2015. There were 4 men and 3 women with a median age of 41 years (range, 19-49 years). All patients presented with a rapidly growing neck mass associated with upper airway compression in 5 (71%) patients. Two patients presented with localized (stage I/II) and 5 patients with disseminated (stage III/IV) disease. All cases showed morphologic and immunophenotypic features of Burkitt lymphoma with MYC rearrangement in all 5 cases tested. One case showed evidence of concurrent Hashimoto thyroiditis. Six of 7 patients were treated primarily with rituximab, hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone. One patient was treated primarily with dose-adjusted rituximab, etoposide, prednisolone, vincristine, and cyclophosphamide. At the end of the study period, 5 patients were alive: 4 in complete remission and 1 with persistent disease. Two patients died with persistent disease (median follow-up, 25 months; range, 12-361 months). We conclude that Burkitt lymphoma of the thyroid gland shows clinicopathologic features similar to sporadic Burkitt lymphoma at other anatomic sites, but patients present at an older median age. The clinical course is aggressive with a high frequency of disseminated disease at diagnosis; however, a subset of patients responds well to aggressive chemotherapy.

Two cases of concomitant acquired aplastic anemia and systemic mastocytosis.

Reactive bone marrow mast cells reliably lack the morphologic, immunophenotypic, and molecular features of systemic mastocytosis (SM). We report two unusual cases of acquired aplastic anemia (AA) in which multifocal aggregates of bone marrow mast cells fulfilled morphologic and immunophenotypic criteria for SM according to the World Health Organization 2008 classification. In the absence of clinical symptoms attributable to SM, the patients were treated with immunosuppressive therapy directed towards AA. Clinical follow-up and subsequent bone marrow examination revealed no evidence of overt SM in either patient. These cases represent, to our knowledge, the first reported instances in which criteria for SM have been fulfilled in the presence of AA. However, given the clinical courses followed by our patients, the incidental identification of mast cell lesions consistent with indolent SM may be of uncertain significance in the setting of AA.