Histologic Findings

In early untreated cases, tissue biopsy samples may show a mild chronic inflammatory infiltration; eosinophils, lymphocytes, and histiocytes may surround the microfilariae. Microfilariae are often present without a surrounding cellular reaction. Later cases show hyperkeratosis, parakeratosis, tortuous dermal vessels, dilated lymphatics, and pigment incontinence. An increased number of dermal fibroblasts leads to perivascular fibrosis. In more advanced cases, hyalinized scar tissue replaces the collagen and elastic fibers in the dermis.

The microfilariae have pointed tails, elongated posterior nuclei, paired anterior nuclei, and large spaces between the tip or tail and the first nuclei. They lack sheaths.

Onchocercomas are made up of an outer vascular fibrous stroma embedded with groups of perivascular leukocytes. The inner layer is composed of hyaline connective tissue intermingled with coiled adult worms. A dense cellular infiltrate composed of eosinophils, lymphocytes, macrophages, and giant cells surrounds the worm. The coiled appearance of the worm, the presence of microfilaria in gravid females, and the presence of a gut help in identifying the worm. See the images below.

Photomicrograph of a skin biopsy specimen from a patient with onchocerciasis. A worm is shown in cross-section. Courtesy of Brooke Army Medical Center teaching file. All images are in the public domain.

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Photomicrograph from a gravid female worm (hematoxylin and eosin]). Courtesy of Brooke Army Medical Center. All images are in the public domain.

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Treatment & Management

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Media Gallery

Leopard-spot pattern of depigmentation on the shins. Courtesy of Brooke Army Medical Center teaching file. All images are in the public domain.
Dermatitis associated with microfilaria. Courtesy of Brooke Army Medical Center teaching file. All images are in the public domain.
Hanging groin sign. Courtesy of Brooke Army Medical Center teaching file. All images are in the public domain.
Hanging groin sign. Courtesy of Brooke Army Medical Center teaching file. All images are in the public domain.
Onchocercoma. Courtesy of Brooke Army Medical Center teaching file. All images are in the public domain.
Onchocercoma. Courtesy of Brooke Army Medical Center teaching file. All images are in the public domain.
Photomicrograph of a skin biopsy specimen from a patient with onchocerciasis. A worm is shown in cross-section. Courtesy of Brooke Army Medical Center teaching file. All images are in the public domain.
Photomicrograph from a gravid female worm (hematoxylin and eosin]). Courtesy of Brooke Army Medical Center. All images are in the public domain.

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Author

Jason F Okulicz, MD, FACP, FIDSA Director, HIV Medical Evaluation Unit, Infectious Disease Service, San Antonio Military Medical Center; Associate Professor of Medicine, F Edward Hebert School of Medicine, Uniformed Services University of the Health Sciences; Clinical Associate Professor of Medicine, University of Texas Health Science Center at San Antonio; Adjunct Clinical Instructor, Feik School of Pharmacy, University of the Incarnate Word

Jason F Okulicz, MD, FACP, FIDSA is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians-American Society of Internal Medicine, Infectious Diseases Society of America

Disclosure: Serve(d) as a speaker or a member of a speakers bureau for: Gilead Sciences.

Coauthor(s)

Dirk M Elston, MD Professor and Chairman, Department of Dermatology and Dermatologic Surgery, Medical University of South Carolina College of Medicine

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

Disclosure: Nothing to disclose.

Robert A Schwartz, MD, MPH Professor and Head of Dermatology, Professor of Pathology, Professor of Pediatrics, Professor of Medicine, Rutgers New Jersey Medical School

Robert A Schwartz, MD, MPH is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, New York Academy of Medicine, Royal College of Physicians of Edinburgh, Sigma Xi, The Scientific Research Honor Society

Disclosure: Nothing to disclose.

Specialty Editor Board

David F Butler, MD Former Section Chief of Dermatology, Central Texas Veterans Healthcare System; Professor of Dermatology, Texas A&M University College of Medicine; Founding Chair, Department of Dermatology, Scott and White Clinic

David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, Association of Military Dermatologists, Phi Beta Kappa, Texas Dermatological Society

Disclosure: Nothing to disclose.

Chief Editor

William D James, MD Paul R Gross Professor of Dermatology, Vice-Chairman, Residency Program Director, Department of Dermatology, University of Pennsylvania School of Medicine

William D James, MD is a member of the following medical societies: American Academy of Dermatology, Society for Investigative Dermatology

Disclosure: Received income in an amount equal to or greater than $250 from: Elsevier; WebMD<br/>Served as a speaker for various universities, dermatology societies, and dermatology departments.

Additional Contributors

Donald Belsito, MD Professor of Clinical Dermatology, Department of Dermatology, Columbia University Medical Center

Donald Belsito, MD is a member of the following medical societies: New York County Medical Society, Noah Worcester Dermatological Society, Phi Beta Kappa, American Contact Dermatitis Society, Dermatology Foundation, Dermatologic Society of Greater New York, Alpha Omega Alpha, American Academy of Dermatology

Disclosure: Nothing to disclose.

Sections Dermatologic Manifestations of Onchocerciasis (River Blindness)
Overview
Presentation
DDx
Workup
Treatment
Medication
Media Gallery
References

Dermatologic Manifestations of Onchocerciasis (River Blindness) Workup

Histologic Findings

References

Tables

Contributor Information and Disclosures

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