Lawrence S. Neinstein, M.D., F.A.C.P.
Professor of Pediatrics and Medicine
USC Keck School of Medicine
Executive Director
University Park Health Center
Associate Dean of Student Affairs



Medical Problems - Dermatology - Quiz (B4)

Go to text

Go to dermatology - acne
Go to dermatology - skin growths
Go to dermatology - hair lesions
Go to dermatology - papulosquamous lesions
Go to dermatology - misc. dermatology lesions
Go to misc. common medical problems
Go to medical problems - orthopedics


Welcome to some common adolescent dermatology unknowns for you to solve.

Skin problems in teens are common and can have a more significant effect on teens than their severity. In fact, some teens with serious chronic medical conditions are more concerned about the skin manifestations of the disease than the life-threatening components.

This first unknown has had this rash for about several months. It is non-pruritic and located only in the area above.

click for full-size image

This is the second unknown. This is a rash on the bearded area of 16 year old teen.

click for full-size image

This is the third unknown. Rash started about two weeks ago. There are no systemic symptoms and teen is feeling well. Rash is non-pruritic.

click for full-size image

This is fourth unknown. The rash started several months ago. It is non pruritic and there are no systemic symptoms .

click for full-size image

This is the fifth unknown. This individual complains of itchy palms for months. There are no systemic symptoms.

click for full-size image

This is the sixth unknown. Teen has had slightly pruritic rash in groin area for several weeks.

click for full-size image

click for full-size image

This is the 7 th unknown and includes lesions on the base of the foot that are painful.

The 8 th unknown is a 16 year old female with history of obesity and irregular menses. Her mother complains that she seems to never wash her neck

click for full-size image

The 9 th unknown is a 17 year old female. She has a history of inflammatory bowel disease that has had an exacerbation in the past several months. She complains of painful lesions on her legs.

click for full-size image

The 10 th unknown is a 15 year old male. He recently had a herpes simplex infection and then developed this rash on his arms.

click for full-size image

The 11 th unknown is a 13-year-old male who complains of penile lesions. He states that he is not sexually active but is afraid that somehow he contacted a STI.

click for full-size image

This last unknown, number 12, is not a specific disease but a lesion on the nail, Please list 2 or 3 conditions associated with this lesion.

click for full-size image


We are ready to discuss the unknowns.

So let's go to the first lesion.

steroid acne
click for full-size image

This appears very similar to acne. It looks like acne and is in the right age group for acne and many of you probably wrote down acne. You are correct in that it is a form of acne. However, it is not acne vulgaris. There are a few things about the lesions that would make you think this might not be acne. Firstly, there are very sharp borders, almost a straight line down the teen's forehead. This does not occur in acne vulgaris. Then, almost all the lesions are in the same stage - also against acne vulgaris. In fact, this teen had steroid acne. She had been applying steroid cream to her forehead for another skin problem and in the area that she applied this cream, she developed acne. You can almost make out the arch of where she applied the cream on her forehead. Sometimes with steroid acne the lesions can all be of the same stage and type.

So on to unknown #2 :

papulopustular lesions
click for full-size image

These are papulopustular lesions that are right next to the hair follicles. This condition is pseudofolliculitis barbae . Pseudofolliculitis barbae is a noninfectious, inflammatory condition usually occurring in males with curly hair. It is caused by the reentry of curved hairs after shaving. While growing a beard will cure this condition, this is not what most teens chose to do. Improvement can occur with some of the following tips:

  • Soften facial hair well with warm water before shaving.
  • The bearded area should be covered with gentle shaving gel before shaving.
  • A special razor can be used and include razors such as the Bump Fighter, the Foil Guard shaver and the PFB razor.
  • A soft-bristled toothbrush can be used in a circular motion on bearded area to dislodge hair tips. This can be done twice a day, before shaving in am and at bedtime.
  • Teen should shave in the direction of beard growth not against.
  • Aftershave lotion should be avoided.
  • Teen can use very mild steroid lotion for very brief period of time. Steroids on face can lead to skin color changes and atrophy.
  • Topical retinoids are sometimes helpful.

Remember unknown #3: This is a papulosquamous lesion. There are many things that can look somewhat like this including allergic reactions, viral infections. This teen below has pityriasis rosea.

pityriasis rosea
click for full-size image

Pityriasis rosea usually starts with Herald's patch and can then spread over trunk and extremities. The condition is a self-limited disorder of unknown cause that frequently occurs during adolescence. It is usually non pruritic or only slightly pruritic. There are usually no associated systemic symptoms. The lesions are oval, salmon colored papular and macular, 1 to 2 cm scaly lesions. They tend to follow the body's lines of cleavage in a sort of "Christmas tree" distribution similar to the picture above. The Herald's patch is usually larger at about 2 to 6 cm and this patch comes 2 to 21 days before the other lesions. Below is example of a Heralds patch.

herald's patch
click for full-size image

papulosquamous lesion
click for full-size image

Ok on to unknown #4

Another papulosquamous lesion. This demonstrates both hypopigmentation in top area and hyperpigmentation in bottom area. This is tinea versicolor . Tinea versicolor is usually hypopigmented or hyperpigmented macules or patches typically over the upper trunk and arms and occasionally on the face and neck. It is caused by Pityrosporum orbiculare. The lesions are usually asymptomatic. Humidity, hyperhidrosis, heredity, diabetes mellitus and systemic corticosteroids can all predispose someone to this condition.

The diagnosis can be made by the observation of hyphae and spores (spaghetti and meatballs) on potassium hydroxide wet mount. A Wood's light examination is helpful in showing yellowish or brownish fluorescence. Treatment can include topical treatments such as selenium sulfide 2.5% shampoo, ketoconazole 2% shampoo, zinc pyrithione shampoo or soap, sulfursalicylic acid. These are usually used in the shower or overnight as tolerated daily for 2 weeks, then several times a month for maintenance. Topical antifungals of the imidazole class also can be used but are expensive for large areas of involvement. Systemic fluconazole 400 mg as a single dose and 200 mg itraconazole daily for 5-7 days have been shown to be effective in treatment of tinea versicolor. However, these medications have not been approved in the United States for the treatment of tinea versicolor.

So this is unknown #5

click for full-size image

Some of you may have thought this might be scabies because of the pruritic nature and the location in the webs of the hands. That is good thought but this is more vesicular and less excoriated in nature than scabies. There are two things that might jump out with these lesions. The first, which is not the diagnosis in this case, is an "id" reaction. This occurs from an immunologic reaction to a dermatophytid. So if one sees lesions like above look at the feet and you might find a rash like this below of tinea pedis.

click for full-size image

The second condition to consider, which is the cause of this condition above, is dyshidrosis or dyshidrotic eczema (pompholyx) which leads to recurrent crops of vesicles on the palms and or soles and sides of the fingers and toes. It is exacerbated by stress and frequent exposure to water. Treatment includes keeping areas dry and occasionally a short course of topical steroids.

Unknown #6 is shown below with and without a Wood's light exam.

click for full-size image

click for full-size image

This rash above is in the groin but while having a sharp border it has no central clearing. This is erythrasma, a superficial bacterial skin infection of intertriginous sites caused by Corynebacterium minutissiumum (short gram-positive diphtheroid). In particular the rash fluoresces a coral red color under a Wood's lamp caused by porphyrin production. A potassium hydroxide preparation may show negative results, but Gram's stain may show Gram-positive filamentous rods (Corynebacterium minutissimum). Treatment is with erythromycin.

OK here is the next unknown #7

plantar warts
click for full-size image

Remember that these were painful lesions on the base of the feet. A couple of things to be thinking about. Obviously calluses could look something like this. However, these are plantar warts. Two things to help in differentiating these two. Calluses can have the skin lines/folds continuing into the lesions, warts do not. In addition, if you pare down the hyperkeratotic area, you will find black dots in the lesion. These are the thrombosed capillaries characteristic of plantar warts.

Treatment: All warts including plantar warts have many types of treatments that all usually have about a 70 to 80% efficacy. About 50% or more of cure relies on the individual's own immune system. Treatment can be very simple for plantar warts and includes paring them down, if they are very thick. Then the patient can buy salicylic acid pads (mediplast pads) and cut them out to the size of the wart. These can be put on for about 24 hours. Several days later, the teen can debride the area with a pumice stone or metal debriding tool. This can be repeated twice a week. Usually over the course of several weeks the warts will resolve.

The next unknown was the following lesion: #8

click for full-size image

The slide below is from another teen with this condition.

acanthosis nigricans
click for full-size image

This condition is acanthosis nigricans. It is associated with obesity and with insulin resistance. One should screen for diabetes in an obese teen with this condition or with a teen with this condition and family history of diabetes. A fasting blood glucose would be a good initial screen.

Acanthosis nigricans usually appears as a gray-brown thickening of the skin. The lesions are symmetrical, velvety, papulomatous plaques, with increased skinfold markings. They are commonly located on the base of the neck axilla, groin, and antecubital fossa. Occasionally, a parent is concerned as to why the teen does not wash themselves.

While in adults acanthosis can suggest a malignancy, the vast majority of acanthosis nigricans lesions in adolescents are not associated with a malignancy and are usually secondary to insulin resistance related to obesity. Weight reduction can reduce these lesions, otherwise the condition is difficult to treat. Lactic acid or alpha-hydroxyacid containing emollients, and tretinoin have been tried but without any controlled studies demonstrating efficacy.

This was unknown #9

erythema nodosum
click for full-size image

The condition above is erythema nodosum. There is a very large differential diagnosis for erythema nodusum. It has been associated with drug reactions including reactions to antibiotics, bromides, oral contraceptives, salicylates and codeine. It has been associated with viral infections, bacterial infections including tuberculosis and fungal infections including cocidiomycosis. It has also been associated with inflammatory bowel disease.

Unknown #10 is associated with target lesions and bullous components.

erythema multiforme
click for full-size image

This is erythema multiforme. The most common associations are post herpes simplex infections, anticonvulsant medications and also post other viral infections such as measles. If two or more mucous membranes are involved, then one has a diagnosis of Stevens Johnsons syndrome.

pink pearly penile pauples
click for full-size image

Below is unknown #11. An important lesion to be familiar with in teens.

These are on the corona of the penis and they are called "pink pearly penile papules. I like to call them PPP on the pp. They are a normal occurrence in about 15% of pubertal and postpubertal males. The lesions are elongated papillae, about 1 to 3 mm in diameter, located on the coronal margin of the penis, especially the anterior border. They often appear in one to five rows and are usually of uniform size and shape. The color tends to be pearly white. They have a normal epidermal appearance microscopically. Condylomata acuminata tend to be of less uniform size and shape, change over time, and are not neatly arranged around the corona of the penis. No treatment is necessary for this condition except reassurance.

The last unknown is pitting of the nails. Several associations include idiopathic alopecia, psoriasis and Reiter's syndrome.

click for full-size image

back to top

Copyright (©) 2004-2013 Lawrence S. Neinstein, University of Southern California . All rights reserved. Republication or redistribution of the text, table, graphs and photos is expressly prohibited. The University of Southern California shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon.