Today, we talked about the case of a middle-aged man from the Philippines who presented with a one year progressive pruritic rash involving the face, arms, and legs as well as a distal symmetric peripheral neuropathy, found to have lepromatous leprosy on skin biopsy!

Clinical Pearls 

• Mycobacterium leprae and lepromatosis like to grow in cooler areas, so infection often manifests in the skin and the peripheral nerves.
• Transmission is likely via respiratory route, through broken skin, and by touching armadillos!
• Early recognition and treatment is important to prevent injury to peripheral nerves.

DDx for rash + neuropathy

• Lyme (usually cranial nerves, radiculopathy)
• Celiac
• Zoster (tends to be painful rather than pruritic and localized to a dermatome)
• WNV (flaccid paralysis)
• Sarcoid
• Amyloid
• Syphilis
• Leprosy

Our patient presented with a pruritic rash and largely a distal symmetric peripheral neuropathy.  We generated the following Venn diagram in report to help us with the diagnosis:

Leprosy

• AKA Hansen’s disease
• Infection caused by mycobacterium leprae and mycobacterium lepromatosis, separate species that cause similar clinical disease. They are both obligate intracellular parasites.
• Involves the skin and peripheral nerves
• Early treatment is important to prevent involvement of the eyes, hands, and feet due to neuropathy. The neuropathy is often non-reversible.
• 205 new cases detected in the US in 2010. 75% among immigrants (most commonly India, Brazil, Indonesia, Bangladesh, and Nigeria)

Transmission

• Unknown but probably respiratory route especially in lepromatous leprosy. Sometimes can transmit through broken skin. Also from armadillos.
• Most people do NOT develop disease after exposure. Risk factor for disease development include older age, genetic influences, and immunosuppression.
• Grows in cooler areas

Clinical presentation:

• Described in categories pertaining to how much bacillary burden of disease is present with tuberculoid being the least amount and lepromatous having the highest disease burden.
• Clinical features:
  • Hypopigmented or reddish patches on the skin
    • Typically involve the earlobes with nodular thickening and distributed symmetrically on the body in lepromatous leprosy.
  • Diminished sensation or loss of sensation within skin patches
  • Paresthesias of hands/feet
    • Neuropathy occurs early in disease course
  • Painless wounds or burns on the hands or feet
  • Lumps or swelling on the earlobes or face
  • Tender, enlarged peripheral nerves
• Late findings in disease course:
  • Weakness of the hands with claw fingers, foot drop, facial paralysis, lagophthalmos (can’t close eyes completely due to CN7 palsy), lack of eyebrows/eyelashes, collapsed nose, perforated nasal septum.
  • Intermittent bacteremia can lead to focal lesions in various organs (liver, bone marrow, testicles and larynx)

Diagnosis:

• Consider it in patients with skin lesions and/or enlarged nerve(s) accompanied by sensory loss.
• No reliable blood or skin tests available.
• Usually clinical and skin biopsy

Treatment:

• Goal: Prevent and/or minimize injury to peripheral nerves!
• Often times it’s loss of sensation but later can progress to painful neuropathy
• Dapsone plus rifampin for tuberculoid leprosy. Clofazimine is added for lepromatous leprosy.
• Duration can be up to 24 months
• Treat neuritis with steroids for a prolonged course
• Make sure to screen for G6PD deficiency before prescribing dapsone
• Monitor liver function with rifampin
• Clofazimine (causes phototoxicity) is not available in US pharmacies and must be obtained from the NHDP.

Prognosis:

• May take a few years for skin lesions to resolve completely with treatment
• Very curable, low relapse rates, typically no drug resistance