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Pseudofolliculitis barbae

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image Introduction Pseudofolliculitis barbae (PFB) (OMIM 612318) is a chronic, non-infectious inflammatory disorder induced by re-entry of curved hair shafts into the skin following hair removal. After shaving, the sharp tip of curved hair shafts can re-enter…

Pruritus vulvae

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image Pruritus vulvae is the external sensation of itching that results in a need to scratch or rub the vulva. Although pruritus vulvae is a common complaint, the etiopathogenesis remains poorly understood. Primary findings are representative of…

Pruritus ani

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image Pruritus ani is characterized by intensely pruritic perianal skin. It is classified into primary (idiopathic) and secondary (induced by an underlying cause). It is common, with incidence ranging from 1% to 5%. Chronic cases are associated…

Pruritus

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image Introduction Chronic pruritus or itch, defined as present for more than 6 weeks, is commonly encountered in the dermatologic clinic and is estimated to affect up to a fifth of the general population at some point…

Prurigo pigmentosa

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image Prurigo pigmentosa (PP) is a pruritic eruption that begins with urticarial papules or papulovesicles on the neck, chest, and back, followed by reticular pigmentation. It most commonly affects women in their twenties and thirties. PP is…

Prurigo nodularis

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image Nodular prurigo (NP; also known as prurigo nodularis [ of Hyde] ) is a chronic condition characterized by the presence of highly pruritic, hyperkeratotic papules or nodules, ranging from a few to hundreds in numbers. Accompanying…

Pretibial myxedema

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image Pretibial myxedema (PM), more accurately termed thyroid dermopathy, is characterized by non-pitting edema and skin-colored to violaceous nodules or plaques. These are most commonly distributed pretibially but can sometimes be seen over the arms, shoulders, head,…

Pregnancy dermatoses

Acknowledgment The authors would like to acknowledge the work of the previous edition’s contributor, Wolfgang Jurecka, MD. Open full size image Dermatoses specifically associated with pregnancy and the puerperium include polymorphic eruption of pregnancy (PEP), pemphigoid gestationis (PG), intrahepatic cholestasis of pregnancy, and atopic eruption of pregnancy. In addition to these classic dermatoses of pregnancy, pregnant women can develop all of the same pruritic dermatoses as…

Postinflammatory hyperpigmentation and other disorders of hyperpigmentation

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image Introduction Hyperpigmentation is a common condition encountered in dermatologic practice. It is defined as darkening of natural skin color and can have a significant impact on quality of life. Hyperpigmentation results from increased melanocyte activity resulting…

Port wine stain (‘nevus flammeus’)

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Courtesy of Herbert Goodheart and Bob Rudolf Open full size image A port wine stain (PWS), also known as nevus flammeus , is a benign capillary malformation (CM) of the superficial cutaneous vasculature. These lesions are almost always congenital, though…

Porphyria cutanea tarda

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports From Lebwohl MG. Atlas of the Skin and Systemic Disease. Churchill Livingstone: Elsevier, 1995. Open full size image The term porphyria cutanea tarda (PCT) encompasses several related inherited or acquired disorders in which deficient hepatic uroporphyrinogen decarboxylase (UROD) enzyme activity…

Porokeratoses

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image The porokeratoses are uncommon disorders of keratinization presenting as keratotic papules or plaques, often pruritic, with hallmark raised keratotic rims histologically characterized as cornoid lamella. The main recognized clinical variants are (1) classic porokeratosis of Mibelli…

Polymorphic light eruption

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image Polymorphic light eruption (PLE) is a highly prevalent photosensitivity disorder, estimated to affect 11–21% people in temperate countries. Typically, PLE appears as a recurrent pruritic eruption comprising papules, vesicles and/or plaques, which occurs on photoexposed skin…

Polycystic ovary syndrome

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image Polycystic ovary syndrome (PCOS) is an endocrine disorder that affects approximately 10% of reproductive-age women. The 2003 Rotterdam criteria are widely used to diagnose PCOS when two of the following three criteria are met: 1) oligomenorrhea…

Pityriasis rubra pilaris

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image Pityriasis rubra pilaris (PRP) is a rare, papulosquamous disorder with a variable presentation and course. It is characterized by follicular hyperkeratotic papules and coalescing salmon-colored plaques with ‘islands of sparing’ that can progress to erythroderma. It…

Pityriasis rosea

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image Pityriasis rosea (PR) is a common, acute, self-limiting, papulosquamous disorder affecting the trunk and extremities. PR is most commonly seen in the 10- to 35-year age group and has a recorded incidence between 0.5% and 2%.…

Pityriasis lichenoides et varioliformis acuta

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image Pityriasis lichenoides et varioliformis acuta (PLEVA) is an eruption of small, erythematous papules that can become vesicular and hemorrhagic. Some ulcerate and necrose, leaving pitted scars. The name refers to the morphology, not the duration, of…

Pityriasis lichenoides chronica

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image Pityriasis lichenoides chronica (PLC) typically consists of small, erythematous papules, which may be purpuric. These develop a characteristic, shiny, mica-like scale attached to the center. They occur predominantly over the trunk and proximal limbs. As the…

Pitted and ringed keratolysis (keratolysis plantare sulcatum)

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image Pitted keratolysis (PK) manifests as shallow, punched-out, circular erosions, primarily on weight-bearing, sweaty areas of the feet, and less commonly on the non-weight–bearing areas of the feet, and on the palms. This superficial infection of the…

Pinta and yaws

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports Open full size image Pinta and yaws belong to the group of neglected endemic and non-venereal treponematoses. These distinct and chronic diseases predominantly affect economically disadvantaged, isolated, rural areas of tropical and subtropical countries. Yaws is currently thought to be…