Cutaneous Protothecosis Workup

  • Author: Sarah K Taylor, MD; Chief Editor: Dirk M Elston, MD   more...
 
Updated: Jul 15, 2010
 

Laboratory Studies

A diagnosis of protothecosis can be made based on findings from either biopsy or culture. Prototheca species readily grow on Sabouraud glucose agar. Smooth, white-to-beige colonies typically demonstrate growth within 48 hours at room temperature. Prototheca species may also be cultured on blood agar, heart-brain infusion agar, or beef infusion broth. Commercial assays that rely on the unique components of the cell wall are also available for identification of Prototheca species.

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Other Tests

No other tests are necessary; however, electron microscopy reveals a double-layered cell wall without chloroplasts. These features differentiate Prototheca organisms from other types of algae.

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Histologic Findings

Protothecosis demonstrates morula formation. Typically, the organisms are 6-10 µm in diameter either outside of the macrophages or within the macrophages. They are best visualized with special stains (eg, periodic acid-Schiff, Gomori methenamine-silver) that are used to highlight fungi. The diagnostic feature of P wickerhamii is the presence of sporangia with a central rounded endospore surrounded by a corona of molded endospores. The appearance of the sporangia is diagnostic, and it is described as moruloid, daisylike, spokelike, and frambesiform.

Note the images below.

Periodic acid-Schiff–stained sections of protothecPeriodic acid-Schiff–stained sections of protothecosis reveal rounded endospores that form characteristic moruloid structures in the dermis. Electron photomicrograph of Prototheca wickerhamiiElectron photomicrograph of Prototheca wickerhamii shows a central rounded endospore surrounded by a corona of molded endospores.

The principal histopathologic differential diagnosis is coccidioidomycosis, which often shows larger sporangia and always shows smaller endospores (2-4 µm).

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Contributor Information and Disclosures
Author

Sarah K Taylor, MD  Staff Physician, Kimbrough Dermatology, Ft George G Meade

Disclosure: Nothing to disclose.

Coauthor(s)

Jon H Meyerle, MD  Assistant Professor, Department of Dermatology, Johns Hopkins University School of Medicine; Chief, Immunodermatology, Dermatology Laboratory Director, Department of Dermatology, Walter Reed Army Medical Center and National Naval Medical Center

Jon H Meyerle, MD is a member of the following medical societies: American Academy of Dermatology and Sigma Xi

Disclosure: Nothing to disclose.

Earl J Glusac, MD  Professor, Departments of Pathology and Dermatology, Yale University School of Medicine

Earl J Glusac, MD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Nothing to disclose.

Specialty Editor Board

Barbara R Reed, MD  Clinical Professor, Department of Dermatology, Dermatology Service, Denver Veterans Affairs Medical Center, University of Colorado Health Sciences Center; Consulting Staff, Denver Skin Clinic

Disclosure: Nothing to disclose.

David F Butler, MD  Professor of Dermatology, Texas A&M University College of Medicine; Chair, Department of Dermatology, Director, Dermatology Residency Training Program, Scott and White Clinic, Northside Clinic

David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Medical Association, American Society for Dermatologic Surgery, American Society for MOHS Surgery, Association of Military Dermatologists, and Phi Beta Kappa

Disclosure: Nothing to disclose.

Christen M Mowad, MD  Associate Professor, Department of Dermatology, Geisinger Medical Center

Christen M Mowad, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, and Phi Beta Kappa

Disclosure: Nothing to disclose.

Catherine M Quirk, MD  Clinical Assistant Professor, Department of Dermatology, University of Pennsylvania

Catherine M Quirk, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Dermatology

Disclosure: Nothing to disclose.

Chief Editor

Dirk M Elston, MD  Director, Department of Dermatology, Geisinger Medical Center

Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Nothing to disclose.

References

  1. Humphrey S, Martinka M, Lui H. Cutaneous protothecosis following a tape-stripping injury. J Cutan Med Surg. Sept-Oct 2009;13(5):273-5. [Medline]. [Full Text].

  2. Walsh SV, Johnson RA, Tahan SR. Protothecosis: an unusual cause of chronic subcutaneous and soft tissue infection. Am J Dermatopathol. Aug 1998;20(4):379-82. [Medline].

  3. Lass-Florl C, Mayr A. Human protothecosis. Clin Microbiol Rev. Apr 2007;20(2):230-42. [Medline].

  4. Lee JS, Moon GH, Lee NY, Peck KR. Case report: Protothecal tenosynovitis. Clin Orthop Relat Res. Dec 2008;466(12):3143-6. [Medline].

  5. Khoury JA, Dubberke ER, Devine SM. Fatal case of protothecosis in a hematopoietic stem cell transplant recipient after infliximab treatment for graft-versus-host disease. Blood. Nov 15 2004;104(10):3414-5. [Medline].

  6. Torres HA, Bodey GP, Tarrand JJ, Kontoyiannis DP. Protothecosis in patients with cancer: case series and literature review. Clin Microbiol Infect. Aug 2003;9(8):786-92. [Medline].

  7. Carey WP, Kaykova Y, Bandres JC, Sidhu GS, Brau N. Cutaneous protothecosis in a patient with AIDS and a severe functional neutrophil defect: successful therapy with amphotericin B. Clin Infect Dis. Nov 1997;25(5):1265-6. [Medline].

  8. Polk P, Sanders DY. Cutaneous protothecosis in association with the acquired immunodeficiency syndrome. South Med J. Aug 1997;90(8):831-2. [Medline].

  9. Yamada N, Yoshida Y, Ohsawa T, Takahara M, Morino S, Yamamoto O. A case of cutaneous protothecosis successfully treated with local thermal therapy as an adjunct to itraconazole therapy in an immunocompromised host. Med. Mycol. Jan 22 2010;[Medline]. [Full Text].

 
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This subtle lesion of cutaneous protothecosis on the shoulder shows an ill-defined, slightly erythematous, thin plaque.
Periodic acid-Schiff–stained sections of protothecosis reveal rounded endospores that form characteristic moruloid structures in the dermis.
Electron photomicrograph of Prototheca wickerhamii shows a central rounded endospore surrounded by a corona of molded endospores.
 
 
 
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