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Clinical Summary

Summer penile syndrome is a benign hypersensitivity reaction involving the skin of the penile shaft. As the name suggests, it is seen during the warm weather months. It is also known as seasonal acute hypersensitivity reaction and lion’s mane penis. The history may include recent play outside in the grass or a wooded area within the last 24 hours. It is most commonly associated with insect bites, usually chiggers, but may also be caused by exposure to plants (poison ivy, sumac, and oak). The diagnosis is made clinically and is suspected when the skin of the shaft of the penis, most often just proximal to the glans, is markedly edematous. There is minimal erythema and no fluctuance. Four out of five patients have pruritus, and few have urinary symptoms. Symptoms (both swelling and pruritus) can last up to 2 to 3 weeks, but most patients have resolution in 4 to 5 days. The differential diagnosis includes trauma, nephrotic syndrome, HSP, balanitis, phimosis, paraphimosis, and priapism.

Management and Disposition

Treatment consists of an oral antihistamine if the patient has pruritus and cool compresses. Systemic corticosteroids should only be considered if the child is in significant pain or is having trouble with the voiding stream. Patients can be discharged home after education and reassurance. Urology involvement and referral is usually not necessary.


  1. Summer penile syndrome is usually painless.

  2. Pruritus is the most common symptom.

  3. Testing is unnecessary, but the diagnosis must be distinguished from paraphimosis.

FIGURE 14.54

Summer Penile Syndrome. Edema of the distal penile shaft and left scrotum. An insect bite is seen at the base of the left mons pubis. (Photo contributor: Lawrence B. Stack, MD.)

FIGURE 14.55

Summer Penile Syndrome. Also known as “lion’s mane penis” due to the marked circumferential edema just proximal to the glans. (Photo contributor: Larry B. Mellick, MD.)

FIGURE 14.56

Summer Penile Syndrome. Swelling and ecchymosis after insect bite in an uncircumcised male with summer penile syndrome. (Photo contributor: Lawrence B. Stack, MD.)

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