What is the role of toxoplasmosis in the etiology of pityriasis lichenoides?

Updated: Sep 11, 2020
  • Author: Jeffrey P Callen, MD; Chief Editor: Dirk M Elston, MD  more...
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Answer

Elevated Toxoplasma gondii titers have been demonstrated in some patients with Mucha-Habermann disease. Despite an absence of clinical infection in case reports and series, more than 80% of primary Toxoplasma infections are asymptomatic, and toxoplasmosis cannot necessarily be dismissed as a causative agent. Note the following:

  • In 1969, Andreev et al were the first to suggest a link between toxoplasmosis and a recurrent PLEVA-like skin eruption in a patient with positive Toxoplasma serologies. [8] Cutaneous lesions reportedly responded favorably to pyrimethamine.

  • In 1972, Zlatkov and Andreev reported 11 patients with PLC and found that test results were positive for toxoplasmosis in 6 patients (55%) using complement-fixations test, intradermal test with toxoplasmin, and Sabin-Feldman dye test. [9] Patients in whom test results were seropositive responded favorably to pyrimethamine, while no improvement was noted in the cutaneous lesions of 3 patients in whom results were seronegative.

  • In 1987, Rongioletti et al described a patient who presented with acute onset of cutaneous lesions and histopathologic findings consistent with PLEVA. [10] Serologic examination demonstrated enzyme-linked immunosorbent assay positivity for IgG and immunoglobulin M (IgM) and weak positive indirect fluorescence test results for IgM (1:16). Giemsa stain on the biopsy specimen failed to demonstrate Toxoplasma cysts. Spiramycin treatment was initiated, and lesions subsided over a few weeks. Convalescent serologies failed to demonstrate IgM 2 months later, although the authors still concluded that Toxoplasma species may have caused the cutaneous eruption.

  • In 1997, Nassef and Hammam reported 22 patients diagnosed clinically and histopathologically with PLC and 20 healthy control subjects. [11] Clinical examination for signs of toxoplasmosis only revealed axillary lymphadenopathy in 2 patients. Eight patients with PLC (36%) had a positive serodiagnosis by indirect hemagglutination versus 10% in the control group, and this difference was statistically significant. Using indirect immunofluorescence antibody tests, the difference was 36% versus 15%, respectively, but the difference was not statistically significant. All 22 patients with PLC were treated with pyrimethamine and trisulfapyrimidine, and lesions in 5 of 8 patients with seropositive results cleared completely within 2 months. None of the patients with seronegative results responded to treatment.


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