Leprosy can damage nerves in the legs and feet months before skin symptoms appear, making diagnosis difficult. According to Gram Research analysis of this case report, a 36-year-old patient experienced severe bilateral lower limb nerve damage initially blamed on vitamin B12 deficiency; his symptoms persisted even after B12 levels normalized, until skin lesions finally appeared and confirmed borderline tuberculoid leprosy. Healthcare providers should consider Hansen’s disease in patients with unexplained nerve damage in endemic regions, even without visible skin changes.
A case report published in Annals of African Medicine highlights an important diagnostic challenge: leprosy (Hansen’s disease) can damage nerves in the legs and feet before any skin symptoms appear. Doctors initially misdiagnosed a 36-year-old patient’s nerve damage as a vitamin B12 deficiency because leprosy typically shows skin changes first. Even after his B12 levels returned to normal, his symptoms continued—until skin lesions finally appeared and a biopsy confirmed borderline tuberculoid leprosy. This case reminds healthcare providers in areas where leprosy is common to consider Hansen’s disease when patients have unexplained nerve damage, even without visible skin problems.
Key Statistics
A case report published in Annals of African Medicine documented a patient whose leprosy caused bilateral lower limb nerve damage for several months before any skin lesions appeared, leading to initial misdiagnosis as vitamin B12 deficiency.
In this 2026 case report, a 36-year-old male’s nerve symptoms persisted despite normalization of vitamin B12 levels, with skin biopsy eventually confirming borderline tuberculoid leprosy as the true cause of his neuropathy.
The case demonstrates that borderline tuberculoid leprosy can present with isolated peripheral nerve damage without cutaneous manifestations, highlighting the diagnostic challenge of atypical Hansen’s disease presentations in endemic regions.
The Quick Take
- What they studied: Whether leprosy can cause nerve damage in the legs without showing skin symptoms first, and how this delays diagnosis
- Who participated: One 36-year-old male patient in an area where leprosy is common, presenting with nerve damage in both lower legs
- Key finding: Leprosy caused severe nerve damage months before any skin lesions appeared, leading doctors to initially blame vitamin B12 deficiency instead
- What it means for you: If you live in or travel to areas with leprosy and develop unexplained nerve pain or weakness in your legs, ask your doctor to test for Hansen’s disease—don’t assume it’s just a vitamin deficiency. Early diagnosis prevents permanent nerve damage.
The Research Details
This is a case report—a detailed medical story about one patient’s experience. Doctors documented how a single patient presented with bilateral lower limb sensory motor neuropathy (nerve damage affecting feeling and movement in both legs) that was initially misattributed to vitamin B12 deficiency. The patient underwent standard medical testing, including blood work and eventually a skin biopsy, which confirmed borderline tuberculoid leprosy as the true cause.
Case reports are valuable because they highlight unusual presentations of diseases that doctors might otherwise miss. In this situation, the patient’s nerve symptoms appeared without the typical skin lesions that usually accompany leprosy, making diagnosis difficult. The case demonstrates the importance of considering less obvious diagnoses when standard treatments don’t work.
This type of research is particularly important in regions where leprosy remains endemic (common). By documenting atypical cases, doctors learn to recognize warning signs earlier and avoid diagnostic delays that can lead to permanent disability.
Case reports serve as early warning systems in medicine. When one patient presents with an unusual pattern of symptoms, it alerts the entire medical community to watch for similar cases. This particular case is important because it shows that leprosy can ‘hide’ behind other diagnoses, and that nerve damage alone—without skin changes—should raise suspicion for Hansen’s disease in endemic areas.
As a single case report, this study cannot prove that leprosy always presents this way or determine how common this pattern is. However, it provides valuable clinical documentation that can guide future diagnosis. The confirmation through skin biopsy (a definitive diagnostic test) strengthens the reliability of the diagnosis. Readers should understand this represents one patient’s experience, not a broad population study.
What the Results Show
The patient presented with bilateral lower limb sensory motor neuropathy—meaning both legs had problems with feeling sensations and muscle control. Initial blood tests showed low vitamin B12 levels, which seemed to explain the symptoms, so doctors treated him for B12 deficiency. However, even after B12 levels normalized through supplementation, the nerve symptoms persisted and worsened.
Months later, skin lesions finally appeared on the patient’s body. A skin biopsy (tissue sample examined under a microscope) confirmed borderline tuberculoid leprosy. This diagnosis explained why the B12 treatment hadn’t worked—the nerve damage wasn’t from vitamin deficiency at all, but from the leprosy bacterium damaging peripheral nerves.
This case demonstrates that leprosy can cause significant nerve damage before producing the skin changes that doctors typically look for. The delay in diagnosis meant the patient suffered longer with progressive nerve damage that could have been treated earlier with appropriate leprosy medications.
The case illustrates how borderline tuberculoid leprosy specifically affects the peripheral nervous system (nerves outside the brain and spinal cord). This form of leprosy has intermediate characteristics between tuberculoid and lepromatous types, which may explain why nerve involvement was prominent while skin manifestations were delayed.
Leprosy typically presents with skin lesions accompanied by or followed by nerve damage. This case is unusual because nerve damage preceded skin symptoms by several months. While medical literature documents that neural involvement can occasionally precede cutaneous (skin) manifestations, such cases are rare and often lead to diagnostic delays, as happened here. This report adds to the growing recognition that atypical presentations of leprosy occur more frequently than previously appreciated.
This is a single case report involving one patient, so findings cannot be generalized to all leprosy patients or even to all cases of borderline tuberculoid leprosy. The report doesn’t provide statistical data on how often this presentation occurs or which patient characteristics make it more likely. Additionally, the case doesn’t compare outcomes between early and delayed diagnosis, though the clinical implications are clear.
The Bottom Line
Healthcare providers in leprosy-endemic regions should consider Hansen’s disease in the differential diagnosis of unexplained peripheral neuropathy, even without visible skin lesions (moderate-to-high confidence based on clinical reasoning and case documentation). Patients with persistent nerve symptoms despite treatment for other conditions should request evaluation for leprosy if they live in or have traveled to endemic areas.
This finding is most relevant to healthcare providers in Africa, Asia, and other regions where leprosy remains endemic. Patients with unexplained nerve damage in these areas should be aware of this possibility. Travelers returning from endemic regions with persistent nerve symptoms should mention their travel history to their doctors.
Permanent nerve damage from leprosy can develop over months if untreated. Early diagnosis and treatment with appropriate antibiotics can halt progression and prevent permanent disability. The patient in this case experienced progressive symptoms over several months before diagnosis—earlier recognition could have prevented additional nerve damage.
Frequently Asked Questions
Can leprosy cause nerve damage without skin symptoms?
Yes, this case report shows leprosy can damage nerves in the legs for months before skin lesions appear. A 36-year-old patient experienced severe bilateral leg nerve damage that was initially misdiagnosed as vitamin B12 deficiency. Skin symptoms appeared later, confirming borderline tuberculoid leprosy.
What should I do if I have unexplained nerve pain in my legs?
See a doctor and mention any travel to leprosy-endemic areas. Don’t assume it’s just a vitamin deficiency—ask specifically about Hansen’s disease testing if standard treatments don’t work. Early diagnosis prevents permanent nerve damage.
How is leprosy diagnosed when there are no skin lesions?
Doctors use blood tests, nerve conduction studies, and skin biopsy. In this case, the skin biopsy confirmed borderline tuberculoid leprosy after months of nerve symptoms. If you have persistent unexplained neuropathy, request comprehensive testing including leprosy screening in endemic areas.
Is leprosy curable if caught early?
Yes, leprosy responds well to antibiotic treatment when started early. The key is recognizing it before permanent nerve damage occurs. This case shows why early diagnosis matters—the patient’s symptoms persisted for months before treatment could begin.
Who is at risk for leprosy today?
People living in or traveling to endemic regions in Africa, Asia, and parts of South America face higher risk. Close contact with untreated leprosy patients increases risk. Most people have natural immunity, but those with weakened immune systems are more vulnerable.
Want to Apply This Research?
- If you have unexplained nerve symptoms, track daily: (1) location and intensity of numbness or tingling (scale 1-10), (2) any new skin changes or lesions, (3) changes in muscle strength or coordination. Log these weekly to share with your healthcare provider.
- If you live in a leprosy-endemic area or have traveled there, add ’leprosy screening’ to your health checklist if you develop unexplained nerve symptoms. Don’t assume nerve problems are always from vitamin deficiencies—ask your doctor specifically about Hansen’s disease testing.
- Set monthly reminders to photograph any skin changes and document nerve symptoms. If you’re being treated for leprosy, track medication adherence and symptom improvement weekly. Share this data with your healthcare provider to ensure early detection of complications.
This case report documents one patient’s experience with an atypical presentation of leprosy. It is not a substitute for professional medical diagnosis or treatment. If you experience unexplained nerve damage, numbness, or tingling, especially if you live in or have traveled to leprosy-endemic regions, consult a qualified healthcare provider immediately. Early diagnosis and treatment are essential to prevent permanent nerve damage. This information is for educational purposes only and should not be used for self-diagnosis.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.