Are You Confident of the Diagnosis?
What you should be alert for in the history
Pinta is one of three endemic treponematoses. It is localized to the Western Hemisphere: Mexico, Central and South America and the Caribbean. Thus, it would be highly unlikely to encounter this disease unless the individual had prolonged residence in an endemic area. During a very protracted course, typically amounting to one or two decades, the patient will have developed widespread psoriasiform lesions that eventuate in a dyschromic residual. Since this disease is unique among the treponematoses in causing only cutaneous disease, the patient should not give a history of constitutional symptoms or symptoms that suggest visceral involvement.
Characteristic findings on physical examination
Analogous to syphilis, physical findings will depend upon the disease stage. Primary pinta consists of a sentinal, fairly large (10 cm), nonpruritic scaly plaque, with a predilection for the lower extremities. The lesion may resolve or persist into the next stage, secondary pinta. The latter is characterized by a generalized papulosquamous eruption. Initially erythematous; individual papules and plaques change to brown, slate blue, black or gray color.(In some countries, affected individuals are called “morados”—the blue ones.) This stage appears 3-5 years after inoculation and waxes and wanes for 2-4 years. Areas of hypopigmentation may be admixed with areas of dark dyschromia (Figure 1). In the tertiary stage, symmetric pigmentary abnormalities appear, ranging from vitiligo-like depigmentation (most common) to variable areas of hyperpigmentation. Bony prominences may be disproportionately affected, especially on the legs.
Expected results of diagnostic studies
Histopathology is nonspecific but suggestive, consisting of mild acanthosis, mild lymphocytic spongiosis, focal basal cell necrosis and a mild dermal infiltrate rich in plasma cells. Corresponding to the clinical findings of dyschromia, basal cells have decreased melanin and abundant melanophages are found within the dermis. Nonspecific seriologic tests (directed toward cardiolipin antigen), such as rapid plasma reagin (RPR) and Venereal Diseae Research Laboratory (VDRL), will be positive. Even specific treponemal tests (microhemagglutination-Treponema pallidum [(MHA-TP], Treponema pallidum immobilization [TPI] are also positive, and may remain so following adequate treatment.
Thus, pinta is serologically indistinguishable from syphilis. While outer-membrane protein gene analysis can distinguish between nonvenereal and venereal treponemes, this degree of laboratory sophistication is not readily available to the clinician.
Primary and secondary pinta can resemble yaws, syphilis, eczema, psoriasis, and lupus when they are recent in onset. Late secondary and tertiary pinta resemble various disease entities with prominent pigmentary alteration: ranging from erythema dychromicum perstans and lichen planus to indeterminate leprosy and vitiligo. The correct diagnosis is based upon positive serologic testing, a history of residence in endemic areas, and compatible clinical lesions. A biopsy may be helpful in eliminating some of the more common diseases in the differential diagnosis.
Who is at Risk for Developing this Disease?
As previously noted, pinta is geographically localized. Although it was once prevalent throughout the Western Hemisphere, this disorder has sustained a marked decline in recent years. It remains endemic in several remote areas of Mexico, western Brazil, and rural Panama.
There is little recent data to pinpoint precise areas of disease persistence. Since protracted direct skin-to-skin contact is required for transmission, children and adolecents who reside in these last remaining edemic foci are at highest risk for developing pinta. Epidemiologic data collected in the 1950’s noted that 25-60% of cases occur in those under 15 years of age.
What is the Cause of the Disease?
Pinta is caused by T pallidum subspecies carateum, a phylogenetic relative of the organism that causes syphilis. It is theorized that the organism enters the host through minor abrasions which have come into direct skin-to-skin contact with an infected individual. This leads to the primary lesion, and hematogenous treponemal dissemination leads to later stages.
Systemic Implications and Complications
This is the only one of the endemic treponematoses that solely affects the skin. Thus, there are neither systemic implications nor complications.
As is true for syphilis, penicillin remains an overwhelmingly effective drug, and thus the treatment of choice. The World Health Organization recommends a single 1.2 million unit dose of benzathine penicillin for both early and late disease; the dose is halved for children younger than 10 years of age. For those allergic to penicillin, oral erythromycin may be given. The pediatric dose of erythromycin is 8-10mg/kg, four times daily, for 2 weeks.
For children older than 10 years of age, and for all adults, the erythromycin dose is 250mg four times daily. Generic tetracycline is also believed effective in the same standard doses given for syphilis. There is no place for surgical intervention nor for physical modalities in managing this infection.
Optimal Therapeutic Approach for this Disease
There is no alternative to antibiotic treatment. Howver, clinical failures of each specific antibiotic therapy have been reported, and alternative agents must be employed in that instance.
Efficay of therapy is judged by healing of any “active” lesions. Depigmented skin does not revert to normal and hyperpigmentation may persist long after therapy has concluded (if not forever). As is true with syphilis, titers of cardiolipin serologic tests may decline following effective treatment, but may also remain weakly positive for life.
Unusual Clinical Scenarios to Consider in Patient Management
The most disturbing and unusual phenomenon associated with pinta is a therapeutic failure. Several such instances are listed in the references. Administration of alternate antibiotic regimens have always proven effective in this scenario.
What is the Evidence?
Marquez, F, Rein, CR, Arias, O. “Mal de pinto in Mexico”. Bull Wld Hlth Org. vol. 13. 1955. pp. 299-32. (Interesting historical read when pinta was much more common than it is at present.)
Stapleton, JT, Stamm, LV, Bassford, PJ. “Potential for development of antibiotic resistance in pathogenic treponemes”. Rev Infect Dis. vol. 7. 1985. pp. S314-17. (Explanation of how resistance can develop and a summary of several such cases.)
Fohn, MJ, Wignall, S, Baker-Zander, Sa. “Specificty of antibodies from patients with pinta for antigens of Treponema pallidum subspecies pallidum”. J Infect Dis. vol. 157. 1988. pp. 32-7. (Laboratory confirmation of the serologic cross-reactivity between endemic treponematosis and venereal syphilis.)
Schmid, GP. “Epidemiology and clinical similarities of human spirochetal diseases”. Rev Infect Dis. vol. 11. 1989. pp. S1460-8. (Reviews evidence for the fact that pinta is only a skin disease without systemic complications.)
Fuchs, J, Milbradt, R, Pecher, SA. “Tertiary pina. Case reports and overview”. Cutis. vol. 51. 1993. pp. 425-30. (Nice illustration of pinta as a mimic for vitiligo. Also reviews typical serologic test results during infection and after therapy.)
Koff, AB, Rosen, T. “Nonvenereal treponematoses: yaws, endemic syphilis and pinta”. J Am Acad Dermatol. vol. 29. 1993. pp. 519-35. (Older review with a wide assortment of pictures. Visual images of these rare diseases speak louder than text descriptions.)
Farnsworth, N, Rosen, T. “Endemic treponematosis: Review and update”. Clin Dermatol. vol. 24. 2006. pp. 181-90. (This is a most recent comprehensive review of all endemic treponematoses. Concise summaries and excellent pictures.)
Harper, KN, Ocampo, PS, Steiner, BM. “On the origin of the treponematoses: A phylogenetic approach”. PLoS Negl Trop Dis. vol. 2. 2008;Jan. pp. e148(Interesting discussion of the evolutionary development of the various treponemal organisms based on genetic composition.)
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