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Media Gallery

A firm, smooth swelling on the scalp.
Surgical removal of an intact pilar cyst through an elliptical excision.
Closure of the defect after surgical removal of the pilar cyst.
The trichilemmal cyst is lined by a squamous epithelium without a granular layer and with swelling of the cells close to the cyst cavity, which is filled with homogenous keratin.
At higher magnification, the cyst is lined by a squamous epithelium without a granular layer and with swelling of the cells close to the cyst cavity, which is filled with homogenous keratin.
Numerous cholesterol clefts are identified within the homogenous keratin of the trichilemmal cyst.
Pilar cyst, low power. The trichilemmal cyst is lined by squamous epithelium without a granular layer (trichilemmal keratinization) and with swelling of the cells close to the cyst cavity, which is filled with homogenous keratin. Calcifications are a common feature.
Pilar cyst, medium magnification. Higher magnification shows the stratified squamous epithelium without a granular layer and shows swelling of the cells closest to the cyst cavity.
Ruptured pilar cyst. A ruptured trichilemmal cyst showing replacement of the squamous lining by histiocytes and rare multinucleated giant cells.
Ruptured, low power. Another ruptured trichilemmal cyst showing replacement of the epithelial lining by granulomatous reaction with numerous cholesterol clefts and calcifications.
Ruptured, high power. Higher-power image highlighting the cholesterol clefts and calcifications.

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Author

Anne Elizabeth Laumann, MBChB, MRCP(UK), FAAD Professor Emerita of Dermatology, Northwestern University, The Feinberg School of Medicine

Anne Elizabeth Laumann, MBChB, MRCP(UK), FAAD is a member of the following medical societies: American Academy of Dermatology, American Academy of Dermatology Association, American College of Wound Healing and Tissue Repair, American Dermato-Epidemiology Network, Association for Psychoneurocutaneous Medicine of North America, Association of Professors of Dermatology, British Association of Dermatologists, Chicago Dermatological Society, Chicago Medical Society, Dermatology Foundation, European Society of Tattoo and Pigment Research, Illinois Dermatological Society, Illinois State Medical Society, Institute of Medicine of Chicago, Lupus Foundation of America, Illinois Chapter, Medical Dermatology Society, National Psoriasis Foundation, National Vitiligo Foundation, North American Rheumatologic Dermatology Society, Rheumatologic Dermatology Society, Scleroderma Foundation, Society for Investigative Dermatology, The Global Fibrosis Foundation, Women's Dermatologic 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

R Stan Taylor, MD The JB Howell Professor in Melanoma Education and Detection, Departments of Dermatology and Plastic Surgery, Director, Skin Surgery and Oncology Clinic, University of Texas Southwestern Medical Center

R Stan Taylor, MD is a member of the following medical societies: American Academy of Dermatology, American College of Mohs Surgery, American Medical Association

Disclosure: Nothing to disclose.

Amanda H Champlain, MD Resident Physician, Division of Dermatology, Loyola University, Chicago Stritch School of Medicine

Amanda H Champlain, MD is a member of the following medical societies: American Academy of Dermatology, American Medical Association, American Society for Dermatologic Surgery, Chicago Dermatological Society

Disclosure: Nothing to disclose.

Sapna M Amin, MD, FCAP Fellow in Dermatopathology, Department of Pathology, Northwestern University, The Feinberg School of Medicine

Sapna M Amin, MD, FCAP is a member of the following medical societies: American Society for Clinical Pathology, American Society of Dermatopathology, Chicago Dermatological Society, College of American Pathologists, Texas Society of Pathologists, United States and Canadian Academy of Pathology

Disclosure: Nothing to disclose.

Acknowledgements

Mohsin Ali, MBBS, FRCP, MRCP, MRCPI Consulting Staff, Department of Dermatology, Amersham General Hospital, UK

Disclosure: Nothing to disclose.

Marjan Mirzabeigi, MD Fellow in Dermatopathology, Department of Dermatology, Northwestern University

Marjan Mirzabeigi, MD is a member of the following medical societies: American Society for Clinical Pathology and College of American Pathologists

Disclosure: Nothing to disclose.

Jenneé A Rommel, MD Resident Physician, Combined Internal Medicine/Dermatology Residency Program, Washington Hospital Center, Georgetown University School of Medicine

Disclosure: Nothing to disclose.

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