A 10-year-old Caucasian child arrives back from her spring break trip with her father. She complains of a generalized slightly pruritic rash that involves her entire body, mostly sparing her face, scalp, and distal limbs. On examination the lesions are noted to be oval or round, about 1 cm or less in diameter, with raised edges and pinkish in color. Some of the lesions seem to have a scale, making the skin look “crinkly.” On her back, the lesions are more oval in shape and appear to align along cutaneous cleavage planes. Upon close questioning the mother, who has primary custody of the child, recalls possibly having seen a single similar lesion on her lower back while she and her daughter were preparing for the upcoming trip.
What is the most likely diagnosis?
What is the best management for this condition?
ANSWERS TO CASE 33: Pityriasis Rosea
Summary: A 10-year-old with a diffuse, slightly pruritic annular rash that developed 10 days after a single large lesion was noted on her lower back.
• Most likely diagnosis: Pityriasis rosea.
• Best management: Supportive care with emollients and occasionally antihistamines if the pruritus is significant.
1. Describe the clinical findings of pityriasis rosea.
2. Know the differential diagnosis for pityriasis rosea.
3. Explain the treatment options for pityriasis rosea.
A new rash on a child can reflect myriad conditions. The initial largish lesion on the back followed 5 to 10 days later by more widespread lesion as described suggest pityriasis rosea. In a sexually active adolescent, consideration for secondary syphilis would be an important consideration.
GUTTATE PSORIASIS: A variant of psoriasis, often following a streptococcal infection, whereby a sudden eruption of small round or oval psoriatic lesions on the trunk, face, and proximal limbs occurs.
NUMMULAR DERMATITIS:Pruritic boggy or vesicular round lesions that erupt on the extremities, buttocks, and shoulders. When chronic, lichenification can occur.
PITYRIASIS LICHENOIDES CHRONICA: Multiple, small (3- to 5-mm), reddish-brown papules covered with grayish scale develop on the trunk and extremities. Its chronicity and lack of herald patch can help distinguish it from pityriasis rosea.
PITYRIASIS ROSEA: Benign childhood skin eruption of oval or round lesions, about 1 cm or less in diameter, with raised edges and pinkish in color, often with a scale on the surface. A “herald patch” is often noted 5 to 10 days prior to the generalized eruption; the generalized eruption often aligns on the back along cleavage planes, resulting in a “Christmas tree pattern.”
Pityriasis rosea is a benign childhood condition. While it is occasionally preceded by a prodrome of fever and malaise, those symptoms rarely require medical attention. Rather, a single round or oval lesion of about 1 to 10 cm in size with a raised border and a scaly appearance (the “herald patch”) occurring anywhere on the body often is the harbinger of more extensive lesion development to occur in about 5 to 10 days. The lesions of the subsequent wide spread eruption occur in crops and are typically less than 1 cm in size, are oval or round, have a raised edge, and are pink to brown in color. On the back, the lesions tend to align along cutaneous cleavage lines resulting in a “Christmas tree pattern.” The herald patch is sometimes confused with a lesion of tinea corporis; a KOH scraping of this lesion will help distinguish the two (Figure 33-1).
Figure 33-1. Pityriasis rosea with the herald patch and the symmetric distribution on the chest. (Reproduced, with permission, from Wolff K, Johnson RA: Fitzpatrick’s Color Atlas and Synopsis of Clinical Dermatology, 6th ed. New York, NY: McGraw-Hill; 2009. Figure 7-1A.)
The cause of pityriasis rosea is unknown, but a viral etiology is suspected. The lesions last from about 2 to 12 weeks and typically are asymptomatic. Treatment consists of a bland emollient, and in the child who does have pruritus, oral antihistamines or topical corticosteroids may be required.
Within the differential for pityriasis rosea is secondary syphilis. Testing for syphilis must be considered in any sexually active adolescent with suspected pityriasis rosea, especially if lesions are found on the palms or soles. Such lesions are unusual in pityriasis but common in syphilis.
Guttate psoriasis is a variant of psoriasis in which children have a sudden eruption of typical psoriasis lesions across their trunk, face, and proximal limbs. These lesions typically are small oval or round lesions that occur following a streptococcal throat or perianal infection. Antibiotic treatment for the streptococcal infection often results in marked skin improvement.
Nummular dermatitis lesions are characterized by extremely pruritic coin-sized lesions, typically on the extremities, buttocks, or shoulders. The lesions can be boggy, vesicular, and weepy or dry and scaly. They are treated similarly to atopic dermatitis, although higher-potency topical steroids are sometimes required. When these lesions occur chronically, lichenification can occur.
Pityriasis lichenoides chronica is considered a benign dermatologic condition of children whereby a generalized eruption of numerous 3- to 5-mm reddish-brown papules covered with grayish scale are found on the trunk and extremities. The lesions can become vesicular, hemorrhagic, crusted, or superinfected. By 2 to 6 weeks these lesions become flat and hyper- or hypopigmented. The lack of the herald patch and the chronicity of the lesions can help distinguish it from pityriasis rosea. Treatment is with lubricants and occasionally topical steroids, and in some children, treatment with erythromycin has hastened its resolution.
Other conditions included in the differential are drug eruptions and viral exanthems. A thorough history might elucidate any medications that are causing a drug eruption, and findings of symptoms related to a viral infection would help assist the diagnosis of a viral exanthema.
33.1 A 4-year-old boy is dismissed from his day care for a rash and comes to the clinic for evaluation. The “rash” is a 2-cm circle on his left cheek that is erythematous, scaly, and has a discrete and raised border. The skin in the middle of the lesion seems unaffected; he scratches it occasionally. He is otherwise healthy and has no serious medical history. His rash is most likely:
A. Nummular eczema
B. Tinea corporis
C. Pityriasis rosea
33.2 A 7-year-old boy, otherwise healthy, presents with 2 weeks of several hypopigmented patches on his face. They are not pruritic, but do seem to have a fine scale. There is no erythema, no crusting, no raised border, and no tenderness. The borders of the hypopigmentation are not sharply demarcated, and there is no other hypopigmentation noted. The most likely diagnosis for this patient is:
A. Atopic dermatitis
C. Tinea corporis
D. Pityriasis alba
E. Nickel dermatitis
33.3 A 15-year-old girl presents to the clinic for evaluation of a rash. She is concerned about a pruritic erythematous lichenified patch below her umbilicus that has waxed and waned for several years. Recently, however, she also developed a similar rash above her umbilicus near the site of a recent piercing. She wonders if the piercing studio didn’t do a good job cleaning their equipment. Her skin condition is most likely:
A. Atopic dermatitis
C. Tinea corporis
D. Seborrheic dermatitis
E. Nickel allergy
33.4 You are asked to consult on a 9-month-old fully immunized infant admitted to the hospital for his third episode of lobar pneumonia. A review of his past history also reveals several episodes of impetigo and otitis media, a chronic diagnosis of atopic dermatitis that has been difficult to control, and a mention of easy bruising. The review of systems identifies occasional oral bleeding after brushing his two new teeth. Laboratory studies show a platelet count of 60,000 platelets/mm3. The most likely diagnosis in this case is:
A. Thrombocytopenia with absent radius (TAR) syndrome
B. Wiskott-Aldrich syndrome (WAS)
C. Idiopathic thrombocytopenic purpura (ITP)
D. Thrombotic thrombocytopenic purpura (TTP)
E. Lichen simplex chronicus
33.1 B. Tinea corporis (also known as “ringworm” describing its characteristic skin finding) is a superficial cutaneous fungal infection caused primarily by Microsporum canis, Trichophyton tonsurans, T rubrum,andT mentagrophytes. The lesion typically starts as an erythematous papule that expands to form a circular, scaly, and erythematous lesion with raised borders. As the lesions get larger, they may develop central clearing. Pruritus is not a universal symptom. Treatment is with topical azoles (eg, ketoconazole, clotrimazole) or systemic antifungals (such as griseofulvin) in more diffuse cases. Pityriasis rosea (PR) and nummular eczema are both in the differential as they can cause circular skin lesions. Patients with PR go on to develop multiple lesions on the trunk in a characteristic pattern, making the clinical distinction clear. Lesions of nummular eczema are discreet, circular, and pruritic; central clearing is not typical.
33.2 D. Pityriasis alba is a common condition in children, manifest by hypopigmented macules with a fine scale, typically found on the face, neck, upper trunk, and proximal upper extremities. Pruritus is usually absent. These lesions are benign, and thought to be a manifestation of dry skin. The lesions are more prominent in dark-skinned individuals, as well as after sun exposure when the surrounding skin darkens and the affected area does not. The borders are not sharply demarcated, distinguishing the lesions from vitiligo. Tinea corporis (ringworm) lesions typically have raised erythematous borders with central clearing. Nickel dermatitis is seen in areas of skin exposed to nickel (under the umbilicus or on the earlobes in pierced individuals). Atopic dermatitis, as described in the initial case, is erythematous, scaly, and pruritic. Treatment of pityriasis alba is skin hydration, and low-dose topical corticosteroids may be used for itching. It is important to inform the patient and family that repigmentation may take months.
33.3 E. Nickel contact dermatitis is seen in areas exposed to nickel, such as the area of skin below the umbilicus that is in contact with the back of snaps and buttons on pants; the neck, in children wearing a necklace; behind the ears, in those wearing glasses; and any site associated with piercing. Affected individuals can avoid inexpensive pierced jewelry and choose instead jewelry with surgical steel posts. The back of pants snaps may be painted with nail polish, thereby preventing skin contact with the offending metal. The location in the vignette is not typical of intertrigo, found in areas of skin apposition.
33.4 B. This patient has Wiskott-Aldrich syndrome (WAS), a rare X-linked disorder characterized by recurrent bacterial infections, bleeding secondary to thrombocytopenia in addition to platelet dysfunction, and chronic dermatitis. The skin findings are identical to atopic dermatitis. Platelet counts usually are between 1000 and 80,000 platelets/mm3, and the platelets are small and dysfunctional. Autoimmune hemolytic anemia occurs in about a third of these patients. The disorder is progressive; without marrow transplantation, most patients die by the age of 3 years. Patients transplanted before the age of 5 have a 71% (matched unrelated donor) to 87% (matched sibling donor) survival rate. TTP is a thrombotic microangiopathy more common in adults, ITP is an isolated thrombocytopenia, and TAR is characterized by the absence of the radius in the forearm and thrombocytopenia; none of these conditions are characterized by the immune dysfunction or the chronic dermatitis seen in the vignette. Lichen simplex chronicus is a chronic localized dermatitis with round or oval lichenified patches; while these lesions may look similar to those described in the clinical vignette of this question, the exposure history makes the diagnosis clear.
Pityriasis rosea is a common eruption in childhood associated with a herald patch.
The lesions of pityriasis rosea align along cutaneous cleavage planes resulting in a “Christmas tree” pattern.
An important diagnosis in the differential of pityriasis rosea is secondary syphilis.
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