Physical Examination and Disease Progression
If the first provider suspected a fungal infection during the initial examination, he should have completed a KOH scraping to confirm that suspicion. While superficial fungal infections are extremely common, particularly in the southeastern US, a sampling of scale with KOH 5% to 20% and the absence of dermatophytes under the microscope might have permitted a quick rule-out.12 Additionally, dermatophytic infections are very responsive to current medications within days, not weeks.
Thus, the key to an accurate diagnosis of leprosy begins with a physical examination that takes into account both chronic unresolved cutaneous lesions and neurologic changes in sensitivity.
A great majority of patients with HD have no noteworthy clinical symptoms until the first skin manifestations. While sensory neuropathy is prominent in all patients, additional findings (depending on the type of leprosy involved) may include plantar ulcers, chronic nasal congestion with early evidence of cartilage loss over the nasal bridge, chronic nosebleeds, cranial nerve palsies, and eye paralysis.12 In rare cases, hypogonadism may develop, or the clinical team may discover amyloidosis, an accumulation of insoluble proteins in the tissues that impairs function in various organs; this condition is usually detected by skin biopsy. If early or indeterminate leprosy is identified, neither form persists; rather, the condition will progress to one of the following:
• Borderline lepromatous leprosy (BL) and lepromatous leprosy (LL) offer very high resistance to treatment and are considered malignant forms of HD. Findings in patients with BL or LL include multiple lesions in various crazy-quilt presentations: macules, papules, plaques, nodules, masses, and patches of deep, erythematous infiltration across the extremities, face, and trunk.12 Loss of all hair except on the scalp is possible. Ulcers may form on the palms of the hands and soles of the feet.
In both BL and LL, results on AFB smears will reflect moderately high or very high concentrations of the pathogen in the patient’s system. Thus, these forms of HD are defined as multibacillary. If either is left untreated, the accumulation of proteins attributed to amyloidosis and secondary infections that develop eventually lead to death.
• Borderline leprosy (BB) has already been described in the case patient, with five or six ill-defined lesions and mild impairment of the peripheral nervous system. Aggressive treatment of this form of HD is important. A strong immune system provides no guarantee of successful treatment, and therapy must forestall a likely continuum to more serious forms.13
• Borderline tuberculoid leprosy (BT) and tuberculoid leprosy (TT) are both forms of paucibacillary HD. They offer little resistance to treatment in the patient with a healthy immune system. Lesions are generally scant (fewer than five; see figure), and the AFB smear reveals 0 to 10 bacteria in 100 fields.12
For the primary care provider, a thorough physical examination also requires familiarity with reasonable differentials. Hallmarks of conditions less likely to be leprosy include nausea, vomiting, or diarrhea, fever and chills, rectal bleeding and unexplained weight loss, headaches, and shortness of breath.
Diagnostic Testing
To help gauge progression of the disease and assess effectiveness of therapy, it is common practice to conduct a neurosensory test at each office visit. This is performed by touching the patient’s extremities and the periphery of lesions with a simple nylon monofilament.13 The patient’s response or lack of response is documented and changes are noted for future therapeutic decision making.
In patients with suspected HD, the NHDP recommends that a full-thickness 4.0-mm elliptical or punch biopsy be performed at the periphery of the largest or most active lesion and that slides be sent to the NHDP in formalin or paraffin for review.14 Experienced NHDP pathologists may order additional stains. A detailed protocol can be found at www.hrsa.gov/hansens/clinical/diagnostics/biopsy.htm.
Proficiency in performing slit smears, a technique to obtain tissue fluid, is also helpful.15 Measurement of the number of bacteria in a set number of fields allows for calculation of the host’s bacterial index, making it possible to determine an appropriate treatment level.
The preferred sites for the slit smear are active lesions, if possible from both ear lobes plus two additional locations. After alcohol swabbing, a tight, bloodless pinch is made, with a 3.0-mm incision that yields blood and fluid. The resulting culture is examined for AFB, which are found abundantly in lepromatous leprosy (whereas tuberculoid leprosy, by definition, should yield none or few). This smear may be repeated at three- to six-month intervals to determine effectiveness of therapy. It is considered superior to a nasal culture, which often yields false-negative results.16
After the Diagnosis
In the US, HD is a nationally notifiable disease: Health care providers are required by law to inform the CDC of the known particulars while complying with HIPAA requirements.17