Risk-Adapted SABR for Ultra-Central Lung Tumors Attaining High BED10 to Targets in a Steep Dose-Response Window of 72-105 Gy under Tumor Tracking: A Planning Study

PURPOSE/OBJECTIVE(S)

Higher rate of durable local control in stereotactic ablative radiotherapy (SABR) for ultra-central lung tumors (UCLTs) strongly correlates to a BED10 ≥ 100 Gy to the tumors. However, higher rates of grade 5 toxicities are reported to be directly associated with higher dose to the organs at risk (OARs) abutting or in close distance to the UCLTs, including trachea, proximal bronchial tree (PBT) and esophagus. This study evaluated two risk-adapted SABR schemes in a steep dose-response window of BED10 at 72 -105 Gy with isotoxic optimization and dynamic tumor tracking to safely attain high BED10 to the tumors while keeping dose to the OARs within evidence-based tolerances.

MATERIALS/METHODS

A total of 12-16 patients are included for planning under two risk-adapted-SABR schemes of 60 Gy in 8 (scheme A) and15 (scheme B) fractions to attain high BED10 of ≥100 Gy to the distal sections of the PTV and yet potent BED10 at 72-84 Gy to the proximal sections of the PTV. Such inhomogeneous dose plans use a 3-5 mm GTV to PTV margins under a scenario that patients have at least one fiducial marker placed in or near the GTV for real-time tumor tracking on a robotic SRS-SABR system. All plans used fixed cone collimators and a planning tool's dose calculation to reach highest BED10 dose coverage achievable to the target volumes while respecting the OAR dose tolerances, including V105 Gy, V100 Gy, V84 Gy and V72 Gy in BED10 for target volumes and the maximum EQD2 dose tolerances (α/β = 3 Gy) in D0.03cc for the trachea/PBT ≤80.5-82.5 Gy and esophagus ≤64.0-77.6 Gy in scheme-A; and trachea/PBT≤97.7 Gy and esophagus ≤64.3 Gy in scheme-B. Median and range of plan dosimetry metrics are compared between the two schemes.

RESULTS

For scheme-A, mean BED10 to PTV are 118.0 Gy (median) in105.5-133.5 Gy (range), and mean BED10 dose to GTV are 132.2 (118.3-149.4 Gy). EQD2 dose to trachea are 80.5 Gy (68.0-81.7 Gy), PBT 80.5 Gy (49.1-82.2 Gy), esophagus 67.2 Gy (51.6-77.3 Gy). PTV coverage by BED10 of 72 Gy, 84 Gy, 100 Gy and 105 Gy are 98.9% (87.5-100%), 97.1% (81.8-99.8%), 91.9% (72.5-98.6%) and 85.3% (68.5-97.9%). For scheme-B, mean BED10 to PTV are 102.2 Gy (93.4-106.0 Gy), and mean BED10 dose to GTV are 115.4 (103.4-117.3 Gy). EQD2 dose to trachea are 73.3 Gy (67.5-96.3 Gy), PBT 90.9 Gy (74.4-97.2 Gy), esophagus 61.4 Gy (41.9-64.1 Gy). PTV coverage by BED10 of 72 Gy, 84 Gy, 100 Gy and 105 Gy are 100% (94.9-100%), 95.5% (83.9-99.0%), 54.8% (31.2-65.4%) and 42.8% (17.9-53.2%).

CONCLUSION

Two risk-adapted SABR of 7.5 Gyx8 and 4 Gyx15 are implemented for treating ultra-central lung tumors with BED10 ≥100 Gy to the distal sections of PTV and yet attain potent BED10 ≥72-84 Gy to the proximal sections of PTV that abut or overlap with trachea, proximal bronchial tree or esophagus. Accurate dose calculation by a planning tool and real-time tumor tracking are essential for safe and accurate delivery of such high-risk SABR treatments.

Impact of a new hospital with close to 100% single-occupancy rooms on environmental contamination and incidence of vancomycin-resistant Enterococcus faecium colonization or infection: a genomic surveillance study

BACKGROUND

Vancomycin-resistant Enterococcus faecium (VRE) is a leading cause of nosocomial infection, driven by its ability to spread between patients and persist in the hospital environment.

AIM

To investigate the impact of a long-established cardiothoracic hospital moving to new premises with close to 100% single-occupancy rooms on the rates of environmental contamination and infection or colonization by VRE.

METHODS

Prospective environmental surveillance for VRE was conducted at five time-points between April and November 2019, once in the original building, and four times in the new building. Incidence rate ratios (IRRs) of VRE infection/colonization were determined for the one-year period before and after the hospital move, and compared to a nearby hospital.

FINDINGS

In the original location, the first environmental screen found 29% VRE positivity. The following four screens in the new location showed a significant reduction in positivity (1-6%; P<0.0001). The VRE infection/colonization rates were halved in the new location (IRR: 0.56; 95% confidence interval: 0.38-0.84), compared to the original location, contrasting with an increase in a nearby hospital (1.62; 1.17-2.27) over the same time-period. Genomic analysis of the environmental isolates was consistent with reduced transmission in the new hospital.

CONCLUSION

The use of single-occupancy rooms was associated with reduced environmental contamination with VRE, and lower transmission and isolation of VRE from clinical samples. The cost-effectiveness of single-occupancy room hospitals in reducing healthcare-associated infections should be reassessed in the context of operational costs of emerging pandemic and increasing antimicrobial resistance threats.

A comparative study of Michel's medium versus honey as a transport medium for skin specimens prior to direct immunofluorescence microscopy and antigen mapping

BACKGROUND

Michel's medium (MM) is currently the recommended transport medium for skin biopsy specimens prior to direct immunofluorescence (DIF) microscopy.

OBJECTIVE

To compare the utility of honey with that of MM as a transport medium for skin biopsy specimens used for DIF and antigen mapping.

METHODS

Group I consisted of 45 freshly-taken skin specimens earmarked for DIF testing. It was divided into three groups (A, B and C), each containing 15 specimens. Biopsy specimens were sliced into two, one each for MM and honey. Samples in group A were processed at the end of week 1 while those in group B and C were processed at the end of weeks 2 and 4, respectively. Group II consisted of five specimens of epidermolysis bullosa (EB) which was further divided into three groups; two specimens were processed for antigen mapping at the end of week 1, while others were processed at the end of week 2 (two specimens) and 4 (one specimen).

RESULTS

Sensitivity of honey as a transport medium for skin biopsy specimens was 100%, 92.6% and 53.8% at weeks 1, 2 and 4, respectively. The antigen mapping was positive in all specimens.

CONCLUSION

Utility of honey was comparable to MM for DIF samples tested at weeks 1 and 2 but was lower at week 4.

Detection of Anti-basement Membrane Zone Antibodies in the Blister Fluid in Subepidermal Autoimmune Bullous Diseases

Background:

Subepidermal autoimmune bullous diseases (sAIBD) are diverse of conditions with clinicopathological overlap. Circulating autoantibodies in the serum can be demonstrated using indirect immunofluorescence (IIF) microscopy. Artificially split normal human skin is considered as an optimum substrate for the demonstration of anti-basement membrane zone (BMZ) antibodies using IIF in sAIBD; it not only helps to detect the presence of circulating antibodies in the serum but also helps to subclassify these conditions into “roof” and “floor” binding disorders.

Aim:

In this study, we evaluated the utility of IIF to detect anti-BMZ antibodies in the blister fluid of patients with sAIBD.

Materials and Methods:

Twenty-two patients with a clinical diagnosis of sAIBD were enrolled in the study. IIF of serum and blister fluid were done simultaneously using salt-split skin as a substrate.

Results:

Anti-BMZ antibodies could be detected in the blister fluid using IIF in all patients in the study group.

Limitation:

We could not do enzyme-linked immunosorbent assay of blister fluid. This would have given us the quantitative data of circulating antibodies in the blister fluid.

Conclusion:

Blister fluid offers an alternate source for the detection of autoantibodies in patients with sAIBD. It may be of particular help in children and in elderly with poor venous access.

Painful erythematous, infiltrated papulonodules in a middle aged man

Cutaneous leiomyomas (CL) often present as painful tumors in the skin. Herein we report an adult man who presented with multiple, erythematous papulonodules in both segmental and non-segmental distribution.

Granular IgM Deposition at Basement Membrane Zone in an Infant with Diffuse Cutaneous Mastocytosis

Diffuse Cutaneous mastocytosis (DCM) occurs due to abnormal accumulation of mast cells in the skin. We report an 8-month-old infant presented papulovesicular lesions, predominantly on the trunk. Skin biopsy revealed subepidermal bulla, interspersed with mast cells, eosinophils and neutrophils. Direct immunofluorescence microscopy of perilesional skin revealed nonspecific deposition of IgM in granular pattern along the dermoepidermal junction.

Cutaneous Sarcoidosis Misdiagnosed as Leprosy. Report of Two Cases and Review of Literature

Cutaneous sarcoidosis may occasionally be mistaken and treated for leprosy. We present two cases of sarcoidosis of the skin which were initially treated as leprosy based on the histopathological features. Histological study in one patient showed perineural and perivascular granuloma adding on to the diagnostic confusion. It is very important for the clinicians to consider sarcoidosis as a possible diagnosis in a patient with clinical features that are not typical of leprosy. Histopathology along with appropriate in -situ techniques can help in arriving at an appropriate diagnosis.

Childhood Epidermolysis Bullosa Acquisita: Confirmation of Diagnosis by Skin Deficient in Type VII Collagen, Enzyme-linked Immunosorbent Assay, and Immunoblotting

Epidermolysis bullosa acquisita (EBA) is an acquired subepidermal bullous disorder characterized by autoantibodies against Type VII collagen. It usually affects adults; childhood EBA is rare. We describe a 10-year-old girl presenting with recurrent tense blisters predominantly on legs, dorsa of hands and feet accompanied by oral erosions since the age of 5 years. Direct immunofluorescence (IF) microscopy showed linear deposition of IgG and C3 along the basement membrane zone (BMZ); indirect IF microscopy on salt-split skin revealed staining of IgG to the dermal side of the split. The patient's serum did not show BMZ staining in recessive dystrophic epidermolysis bullosa skin deficient for Type VII collagen, thus confirming autoantibody reactivity against Type VII collagen. Circulating antibodies against the immunodominant noncollagenous 1 domain of Type VII collagen were detected by ELISA and immunoblotting studies. The patient was treated with oral corticosteroids and dapsone with good improvement.

Pseudomonas aeruginosa meningitis/ventriculitis in a UK tertiary referral hospital

BACKGROUND

Pseudomonas aeruginosa is a rare cause of meningitis and ventriculitis but is generally associated with significant morbidity and mortality.

AIM

We sought to determine the epidemiology, risk factors and outcome of meningitis and ventriculitis due to P. aeruginosa at our institution in order to inform preventive strategies and treatment guidelines.

METHODS

Retrospective study of all patients with a positive cerebrospinal fluid (CSF) culture admitted to a tertiary care hospital over 18 years. Clinical details, demographic, microbiological and antibiotic data were obtained from laboratory and medical records.

RESULTS

Twenty-four episodes occurred in 21 patients over 18 years. Pyrexia (75%), fluctuating mental status (50%) and headache (41%) were the most frequent presenting symptoms. Nineteen of the 21 patients had previously undergone a neurosurgical procedure and seven had extra-ventricular devices in situ. Twelve (57%) patients had P. aeruginosa isolated from another site prior to their episode. Most (89%) CSF samples demonstrated a neutrophilia; the CSF protein, when measured, was raised in all cases. Gram-negative bacilli were visible on CSF microscopy in only three isolates. There were relatively low rates of resistance to most antimicrobials tested and combination treatment of intravenous with intrathecal antibiotics was often used. No patients died within 28 days.

CONCLUSION

Pseudomonas aeruginosa meningitis and ventriculitis are predominantly nosocomial and related to prior neurosurgery. It can be difficult to diagnose as CSF Gram-film and meningism are insensitive markers. Appropriate empirical treatment, neurosurgical prophylaxis and surveillance can aid in managing this infection.

Co-infection as a confounder for the role of Clostridium difficile infection in children with diarrhoea: a summary of the literature

Although Clostridium difficile is a major cause of antibiotic-associated diarrhoea in adults, the incidence and severity of C. difficile infection (CDI) in children is unclear. One complicating factor in assessing the role of CDI in children is the possibility of co-infection with other gastrointestinal pathogens. In this review, we summarise the literature concerning C. difficile co-infections in young children, in an attempt to discuss the rate of co-infections and their potential role in the severity of CDI clinical presentation. We identified 31 studies where co-infections were analysed, comprising 1,718 patients with positive C. difficile tests. The pooled percentage of reported co-infections was 20.7% (range 0-100%). Viral co-infections were most commonly reported (46%), with bacteria and parasites accounting for 14.9% and 0.01% of cases, respectively. However, the panel of co-infections tested for varied considerably among studies and 38% of stated co-infections did not have a pathogen reported. Substantial variation in how and when tests for gastrointestinal co-infections are carried out, small sample sizes and a lack of clear CDI case definitions preclude meaningful conclusions on the true rate of co-infections in this patient population. This review suggests that co-infections may be common in children with diarrhoea who tested positive for C. difficile. Given a lack of CDI case definitions, especially in young children under the age of 5 years, a broad panel of pathogens should be tested for to exclude other microbiological causes. However, the summarised poor quality of the available literature on this subject highlights a need for further studies.

Acantholytic Variant of Bowen's Disease with Micro-invasive Squamous Cell Carcinoma: A Case Report of a Unique Variant

Bowen's disease is generally regarded as premalignant dermatoses. The disease affects both skin and the mucosa and has the potential to progress to invasive squamous cell carcinoma. There are descriptions of several histological variants of Bowen's disease like psoriasiform, atrophic, pagetoid, etc. Acantholysis of anaplastic keratinocytes with bullae/cleft formation is described in premalignant condition like actinic keratosis and adenoid variant of squamous cell carcinoma, but there is lack of report describing this phenomena in Bowen's disease. We present a case of unusual acantholytic variant of Bowen's disease with focus of micro-invasive carcinoma.