Clinico-histopathological concordance in leprosy

Evaluation of Auramine O staining and conventional PCR for leprosy diagnosis: A comparative cross-sectional study from Ethiopia

BACKGROUND

Diagnosis of leprosy mainly relies on clinical examination due to the inconsistent sensitivity and poor reproducibility of the current laboratory tests. Utilisation of alternative methods to the standard Ziehl Neelsen (ZN), Fite-Faraco (FF) and Haematoxylin and Eosin (H&E) staining procedures may eventually improve leprosy diagnosis.

METHODOLOGY/PRINCIPAL FINDINGS

In this comparative study, the performance of the fluorescent Auramine O (AO) staining and polymerase chain reaction (PCR) was assessed with different skin samples using a combination of ZN, FF and H&E staining as the gold standard. AO, ZN, FF, H&E and PCR tests were performed on slit skin smears (SSS) and/or punch biopsies collected from 141 clinically confirmed leprosy cases and 28 non-leprosy skin samples. DNA was extracted from punch biopsies using two different methods with or without mechanical lysis. Sensitivities were 87.6%, 59.3% and 77% for H&E, ZN and FF, respectively, whereas it reached 65.5% and 77.9% for AO in SSS and tissue sections and 91.1% for PCR in tissue samples. Morover, samples with low bacillary index, sensitivity of AO staining (61.8%) was similar to FF (60%, p>0.05) and lower than PCR (86.6%, p<0.05). Sensitivity of PCR also increased (96.8%, p<0.05) when mechanical lysis was used during DNA extraction compared to enzymatic treatment alone (84.6%).

CONCLUSIONS/SIGNIFICANCE

Our results showed that for diagnostic purposes, analysis of skin section is more sensitive than SSS, especially for samples with low bacillary load. AO staining on SSS and tissue sections was not significantly better than other routine diagnostic tests but considerably more user friendly. The sensitivity of PCR was higher than current standard methods and increased when combined with more efficient DNA extraction using mechanical and chemical lysis. Therefore, we recommend AO staining for the diagnosis of leprosy in lower health facilities such as health centres and district hospitals and PCR diagnosis at referral level and research centres.

Role of surgeons in determining outcome of histopathology specimens

Background:

In the changing world of clinicopathologic practice where surgeons and pathologists are faced with increasing therapeutic demands, precise demands of each group from the other have often been reduced to blames and counter-blames. This study is thus aimed at auditing the current practice of specimen handling as a means of highlighting areas where mutual best practice is required.

Materials and Methods:

A total of 200 specimens and 100 separate request cards received over the 3 months were audited for: Use of fixative, adequacy of fixative used, types of specimen containers and appropriate labeling of containers. The request cards were audited for: Documentation of patients’ hospital numbers, ages, histories of disease, sites of biopsy, examination findings, investigations done, provisional diagnosis and concordance of clinical diagnosis with histopathological diagnosis.

Results:

About 20% of specimens were unfixed, 23.5% had inadequate fixative, 16.5% were in inappropriate containers and 32.5% were incompletely labeled respectively. In 25%, 50% and 53% of forms the age, clinical history and examination findings respectively were not documented. Provisional diagnosis was in concordance with eventual histological diagnosis in 69% of cases.

Conclusion:

To ensure the quality of histopathological diagnosis with minimal turnaround time, the surgeon plays a vital role by ensuring adequate and prompt fixation of tissue biopsies, put in the right container and accompanied by well labeled request cards.

Evaluation of the agreement between clinical and laboratorial exams in the diagnosis of leprosy

This study examined the correlation between the clinical and laboratory diagnosis of leprosy, using biopsy results from laboratories 'A' and 'B' and the ML Flow test. Clinical and histopathological diagnoses presented 67.6% agreement. The laboratories showed 73.7% agreement in the bacterial index and laboratory 'B' detected 25.4% more positives. The highest agreement was in the LL form and lowest, in the I form. The highest diagnostic discrepancy was for the BB form. Clinical diagnosis agreement was 41.3% for laboratory 'A' and 54% for 'B'. The ML Flow test reclassified 10.7% of the patients. The spectrum of leprosy classification is important for a clearer understanding of the disease and its proper treatment, but is not used in health services, which use the simplified WHO criteria. This could be complemented by ML Flow testing. Such simplification is unacceptable for Leprosy Reference Centers regarding patient attendance, teaching and research, for which the standardization of the Ridley-Jopling classification is recommended.