Borderline tuberculoid leprosy mimicking sarcoidosis: A case report

Lepra Reactions: Mimickers and Mirror to Unmask Complex Cases of Leprosy

Leprosy is a silent disease with protean manifestations, especially during lepra reactions (LRs). Cases with atypical leprosy or LR simulate a number of conditions misdiagnosed frequently. Here, three classical cases of leprosy are reported for their complex presentation. Leprosy was hidden in Case 1 due to co-existing diabetes. COVID vaccination induced LR unmasked all leprosy lesions, which were extensive, large, bizarre and spreading to various immune zones. Case 2 presented with high-grade fever, tachycardia, generalized erythema and body aches. A detailed workup unveiled his leprosy with a rare presentation of Type 1 lepra reaction (T1LR) with erythroderma and severe systemic symptoms. Case 3 mimicked sarcoidosis and lupus erythematosus (LE) on routine workup. She had facial lesions in the malar area, photosensitivity, joint pains, raised angiotensin-converting enzyme (ACE) levels and positive anti-nuclear antibodies. Peri-appendageal granulomas on histopathology and therapeutic response to multidrug therapy helped in the early diagnosis of leprosy.

Sarcoidosis with cutaneous perineural granulomas and neurological manifestations: A potential mimicker of leprosy

Sarcoidosis is a granulomatous condition with diverse clinical presentations, including neurological findings. It was previously hypothesized that perineural sarcoidal granulomas in the skin may be an explanation of small-fiber neuropathy. Herein, we present a case of a 55 year old female with anesthetic cutaneous lesions mimicking leprosy clinically and histopathologically and discuss the importance of this differential diagnosis.

Develop and Field Evolution of Single Tube Nested PCR, SYBRGreen PCR Methods, for the Diagnosis of Leprosy in Paraffin-embedded Formalin Fixed Tissues in Yunnan Province, a Hyper endemic Area of Leprosy in China

Background

Detection and pathology analysis of Mycobacterium leprae using skin biopsy tissues are essential for leprosy diagnosis and monitoring response to treatment. Although formalin fixation of patient tissues may not be ideal for molecular studies, biopsy samples are the most accessible material from suspected cases. Therefore, clinical molecular laboratories must be able to utilize formalin-fixed, paraffin-embedded (FFPE) material.

Objective

To determine the best molecular method for diagnosing and monitoring leprosy in FFPE specimens, we developed a single-tube nested PCR (STNPCR) (131 bp) and SYBRGreen PCR (101 bp) assay using primers for the M. leprae-specific repetitive element (RLEP) gene and evaluated the results compared to those using previously established RLEP primers (372 bp).

Methods

FFPE biopsy samples obtained from 145 leprosy patients (during or after multidrug therapy (MDT)) and patients with 29 other confounding dermatoses were examined by the bacteria index (BI) and by simple PCR, STNPCR, and SYBRGreen PCR using primers amplifying a 372-bp, 131-bp or 101-bp fragment of RLEP, respectively.

Results

In leprosy patients receiving MDT, STNPCR showed a highest specificity of 100% and a positive predictive value (PPV) of 100%. For multibacillary (MB), paucibacillary (PB) and all leprosy patients, the highest sensitivities were 91.42%, 39.13%, and 67.92%, negative predictive values (NPVs) were 8.57%, 60.36%, and 32.07%, and the highest accuracies were 93.93%, 62.67%, and 74.81%, respectively, higher than the results of SYBRGreen PCR and simple PCR. For post-MDT leprosy patients, SYBRGreen PCR showed the highest sensitivity of 50.0%, highest specificity of 100%, a PPV of 100%, an NPV of 100% and the highest accuracy of 83.72% for MB patients, which were higher than those of STNPCR and simple PCR. STNPCR showed the highest sensitivity of 26.66% and 34.48%, highest specificity of 100% and 100%, a PPV of 100% and 100%, NPV of 72.50% and 60.21%, and highest accuracy of 75.00% and 67.24% for PB and leprosy patients, respectively, higher than those of SYBRGreen PCR and simple PCR.

Conclusions

These findings suggest that STNPCR or SYBRGreen PCR (131-bp and 101-bp fragment amplification, respectively) for RLEP using FFPE specimens performs better as a diagnostic test and for monitoring response to MDT than does simple PCR based on 372-bp fragment amplification. Additionally, STNPCR showed increased sensitivity for PB diagnosis using FFPE specimens, which can be transferred remotely or retrieved from previous leprosy patients.

Leprosy is one of the oldest diseases known to humankind and is caused by Mycobacterium leprae. Despite being curable, leprosy is still a notorious disease, causing serious disability and a stigma generally associated with late diagnosis. The disease is challenging to diagnose because there is no gold standard method for detecting M. leprae or its cellular components (DNA, lipids or proteins). In past decades, different PCR methods were developed to amplify different M. leprae gene targets, such as the RLEP gene, with high sensitivity in leprosy diagnosis using skin biopsy and slit skin smear (SSS) specimens. However, few reports have focused on FFPE specimens. Because FFPE specimens can be transferred remotely or retrieved from previous leprosy patients, we developed and evaluated the STNPCR assay for detecting M. leprae in these specimens. Our results suggest that STNPCR of RLEP using FFPE specimens performs better as a diagnostic test and for monitoring response to MDT than does simple PCR.