Lichen planus (LP) is an idiopathic Idiopathic Dermatomyositis, cell-mediated inflammatory skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions disease. It is characterized by pruritic, flat-topped, papular, purple skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions lesions commonly found on the flexural surfaces of the extremities. Other areas affected include genitalia, nails, scalp, and mucous membranes. Exact etiology is unknown but has been found to be associated with hepatitis C Hepatitis C Hepatitis C is an infection of the liver caused by the hepatitis C virus (HCV). The infection can be transmitted through infectious blood or body fluids and may be transmitted during childbirth or through IV drug use or sexual intercourse. Hepatitis C virus can cause both acute and chronic hepatitis, ranging from a mild to a serious, lifelong illness including liver cirrhosis and hepatocellular carcinoma (HCC). Hepatitis C Virus infection, other diseases, and multiple drugs. Skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma of the most prominent lesion is used for confirmation of the diagnosis. Cutaneous LP usually resolves in 1–2 years. Other forms, however, are chronic and persistent. Topical corticosteroids Corticosteroids Chorioretinitis are the preferred treatment.
Last updated: 8 Jan, 2021
Lichen planus of the back of an 11-year-old African American boy with a 6-year history of generalized LP. Note the presence of the Koebner phenomenon: the spread of LP lesions along areas of trauma, including scratches on the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions.
Image: “12186” by CDC. License: Public DomainLichen planus on bilateral wrists
Image: “6545” by CDC/ Susan Lindsley. License: Public DomainLichen planus presenting as Wickham’s striae on the oral mucosa Oral mucosa Lining of the oral cavity, including mucosa on the gums; the palate; the lip; the cheek; floor of the mouth; and other structures. The mucosa is generally a nonkeratinized stratified squamous epithelium covering muscle, bone, or glands but can show varying degree of keratinization at specific locations. Stomatitis
Image: “12632” by CDC/ Robert E. Sumpter. License: Public DomainLichen planus: epidermis Epidermis The external, nonvascular layer of the skin. It is made up, from within outward, of five layers of epithelium: (1) basal layer (stratum basale epidermidis); (2) spinous layer (stratum spinosum epidermidis); (3) granular layer (stratum granulosum epidermidis); (4) clear layer (stratum lucidum epidermidis); and (5) horny layer (stratum corneum epidermidis). Skin: Structure and Functions shows hyperkeratosis Hyperkeratosis Ichthyosis Vulgaris, hypergranulosis, acanthosis, and saw-tooth rete ridges Rete Ridges Lentigo Maligna. Dermis Dermis A layer of vascularized connective tissue underneath the epidermis. The surface of the dermis contains innervated papillae. Embedded in or beneath the dermis are sweat glands; hair follicles; and sebaceous glands. Skin: Structure and Functions shows a band-like Band-Like Tension Headaches lymphocytic infiltrate touching the epidermis Epidermis The external, nonvascular layer of the skin. It is made up, from within outward, of five layers of epithelium: (1) basal layer (stratum basale epidermidis); (2) spinous layer (stratum spinosum epidermidis); (3) granular layer (stratum granulosum epidermidis); (4) clear layer (stratum lucidum epidermidis); and (5) horny layer (stratum corneum epidermidis). Skin: Structure and Functions (H&E stain, ×40).
Image: “Lichen planus” by Department of Pathology, JJ Hospital, Mumbai, India. License: CC BY 2.0Histopathology of a skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma of an LP plaque Plaque Primary Skin Lesions showing dense lichenoid inflammatory infiltrates underneath the lamina propria Lamina propria Whipple’s Disease. Note the inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation at the dermal–epidermal junction Dermal–Epidermal Junction Bullous Pemphigoid and Pemphigus Vulgaris and an angulated zigzag lower contour, which gives it the saw-tooth appearance characteristic of LP. Note also the thickening of the granular cell layer (hypergranulosis) and the stratum corneum Stratum corneum Skin: Structure and Functions ( hyperkeratosis Hyperkeratosis Ichthyosis Vulgaris), which are more pronounced in the white lines of Wickham’s striae.
Image: “Histopathology of lichen planus” by Shi G, Sohn KC et al AL Amyloidosis. License: CC BY 4.0, edited by Lecturio.