10-year-old (female) with Rash on Scalp

00:00 Okay, guys, we have a question here that I have personally seen on boards twice, so let’s tackle this one.

00:08 A ten year old female comes to the office with her mother complaining of a circular itchy rash on her daughter’s scalp for the past three weeks.

00:19 Her mother is also worried about her daughter’s hair loss.

00:23 The girl has a past medical history significant for asthma.

00:28 She needs to use her albuterol inhaler once per week on average.

00:33 Her blood pressure is a 112/70, the heart rate is 104, the respiratory rate is 20 and the temperature is 37°C.

00:45 On exam, the patient is alert and interactive.

00:49 Her lungs are clear to auscultation bilaterally.

00:53 On palpation a tender posterior cervical node is present on the right side.

01:00 Examination of the head is shown in the image.

01:04 Which of the following is the best treatment option for this patient? Answer choice A: Subcutaneous triamcinolone.

01:15 Answer choice B: Ketoconazole shampoo.

01:20 Answer choice C: Oral doxycycline.

01:24 Answer choice D: Oral terbinafine, or Answer choice E: Topical betamethasone.

01:33 Now take a moment to come to the answer by yourself before we go through it together.

01:40 Okay, this is a very important question.

01:44 I have seen this question on my Family Medicine Shelf Exam and I have even seen it on my own USMLE exam.

01:52 I don’t know why this question is so popular, but boy, let me just tell you, you better learn it.

01:58 Okay, let’s go through the question characteristics.

02:01 Now this is a family medicine question and it’s a two step question.

02:06 The first thing we have to do is figure out the diagnosis and then second we have to figure out the best treatment.

02:13 Now this is another one of those USMLE questions in which many treatments options in the answer choices maybe valid but it is our job to figure out the single best choice for this patient and of course the stem is required because we need to shuffle through all the components of the question stem to come to the diagnosis and then subtly figure out the best treatment option.

02:39 So let’s walk through this question together. Now the first thing we need to do is determine the diagnosis.

02:46 Now we have a female pediatric patient coming to us with the chief complaint of a rash on her scalp.

02:54 Now, the rash characteristics, just take a look at the photo, is that it’s circular, it’s erythematosus, it’s causing hair loss, that’s also just called alopecia.

03:05 It’s scaly, and we're told that it’s itchy.

03:09 Now, the physical examination also picked up that there was cervical lymphadenopathy on the posterior cervical node on the patient’s right side.

03:22 Now, this alone puts us at a pretty wide differential diagnosis position.

03:29 Now, what you may be thinking is what’s called alopecia areata which is essentially spot baldness.

03:38 You may be thinking of atopic dermatitis, psoriasis, seborrheic dermatitis or even tinea capitis.

03:46 Now, from this wide differential, we can kinda start to eliminate things right away.

03:52 Now, Alopecia areata is going to be unlikely because in those conditions you just simply have hair loss, you don’t have any epidermal changes or inflammation.

04:04 And also atopic dermatitis is also going to be unlikely as it’s also not commonly circular or associated with lymphadenopathy.

04:16 It’s generally actually associated with other types of atopy.

04:21 Now, psoriasis for this patient is also, also going to be unlikely as it is not usually associated with alopecia or lymphadenopathy and usually gives you more than just one lesion.

04:38 Now, when you look at this patient, tinea capitis is the most likely thing to be consistent with this patient’s presentation.

04:49 The rash characteristics looks like tinea capitis, the patient’s age and most importantly the associated lymphadenopathy is very consistent with tinea capitis and that’s the diagnosis that’s correct.

05:05 Now that we know this patient has tinea capitis, what we need to figure out is, what’s the best treatment option for this patient? Now tinea capitis is a fungal infection and thus we need anti-fungal treatment.

05:19 Now, looking at the answer choices, you can just right away eliminate the non-antifungal answer choices that is Answer choice A, subcutaneous triamcinolone and Answer choice E, topical betamethasone can both be eliminated cuz those are both steroids and we can also eliminate Answer choice C, oral doxycycline, cuz that’s an antibiotic that’s used for bacterial and protozomal infections.

05:52 Now, what’s left are the antifungal treatments for tinea capitis which the correct answer here being oral terbinafine, but if you look at the answer choice you can say to yourself, hey, wait a minute? Ketaconozole shampoo is also on their but, though ketoconazole shampoo has been showed to be effective for tinea capitis, it’s not as effective as oral terbinafine and that’s the money maker of this question.

06:24 You really need to figure out that it’s tinea capitis and you should be narrowing it down to the oral terbinafine or topical ketoconazole and then you need to know the actual guidelines here state that oral terbinafine is superior and more effective than the ketaconozole shampoo.

06:44 You need to memorize that. I have seen it twice now on boards, it’s talked about all the time, important to know.

06:51 Now, let’s go a little bit more into detail regarding some of our answer choices.

06:55 Now, like we had mentioned, this patient’s presenting with the clinical manifestations of tinea capitis which is a fungal infection of the scalp.

07:06 Now, this fungal disorder is most prevalent in male children but can absolutely also occur in female patients.

07:16 Now, Tinea capitis frequently results from a fungal infection from the Trichopython or Microsporum family with Trichopython tonsurans being the most likely causing of agent that’s going to cause this dermatophyte.

07:34 Now the clinical features that are often observed in tinea capitis include the infection causing the patient to feel pruritic or itchy.

07:44 You can have scaly plaques that grow in a centrifugal fashion as you can see in the picture, it’s this circle style for at least a few weeks.

07:55 Now, Alopecia as well as erythema can also be observed in patients that have tinea capitis.

08:04 Now, if you’re in doubt of the diagnosis of clinically from history and appearance of the rash, you can’t figure it out, you can actually take a skin sample and do a potassium hydroxide prep to confirm the presence of hyphae under microscope because tinea capitis is a fungal infection and hyphae are seen in fungi.

08:29 Now oral terbinafine is our answer of choice here because it’s an inhibitor of squalene epoxidase and it’s considered the most effective treatment for tinea capitis.

08:42 Now let’s look at some of our other answer choices.

08:45 Now answer choice A, subcutaneous triamcinolone which is essentially subcutaneous steroids.

08:51 Now if a patient comes in with alopecia aerata, that can often be mistaken for tinea capitis because it’s often in our differential, but alopecia areata does not exhibit the scaling plaques that grow in a centrifugal fashion that we see with tinea capitis and also, its most commonly going to be seen before the age of 30 and then the areas of alopecia, will actually form a circular fashion over time in weeks and then subsequently they can have a sensation of pruritus and burning and hopefully, there you can see why we included it in our differential.

09:33 What’s interesting as an important buzz word for you to know, that alopecia areata has what’s called exclamation point hairs which are a few hairs that are a few millimeters in length with a thick distal end and a thin proximal end that are very noticeable in alopecia areata, so that is the exclamation point hairs, so look out for that in future questions.

10:02 Now, the diagnosis here really is made based on physical exam or you can do a skin biopsy but you don’t really need to and treating alopecia areata includes injecting subcutaneous triamcinolone to try to promote hair growth in this regions.

10:19 Now let’s look at Answer choice B, ketoconazole shampoo - now that’s going to be important for seborrheic dermatitis of the scalp but which can actually also can be confusing for tinea capitis.

10:31 Now throughout life, seborreic dermatisis most often affects males during infancy, adolescense and adulthood and the clinical features here includes seborreic dermatitis can be as mild as just simply dandruff or a severe as a pruritic gray to orange clock-like lesions that are covered by greasy scales and the treatment for this seborrheic dermatitis is ketoconazole shampoo.

11:03 Now looking at Answer choice C, there is a condition called dissecting cellulitis of the scalp, formerly called Hoffmann’s disease, in which you actually have alopecia and it present most commonly in African American males between ages 20 to 40 years of age and what actually happens here is you have sinus tracks that interconnect suppurative nodules that are usually located in the vertex, which means the very top of the head, or the occipital regions of the scalp.

11:39 Now, you treat dissecting cellulitis of the scalp with tetracycline antibiotics such as doxycycline or minocycline.

11:49 And then lastly, looking at Answer choice E which is the topical betamethasone which is a steroid, you can have a condition called scalp psoriasis or just psoriasis involving the scalp and that’s more common in young females than it is seen in males, and for those children that have psoriasis, scalps psoriasis is actually seen in 80% of cases of the psoriatic patients and the features of scalps psoriasis including well demarcated erythematous scaly plaque that is typically found at the border of the hairline and the treatment of scalp psoriasis includes topical betamethasone.

12:33 Okay, guys, now let’s talk about some high yield facts for this question.

12:38 The first thing to talk about is tinea capitis.

12:41 Now, this is a fungal infection of the scalp and very high yield to know, this may sounds like my new show, but people like to asked about it, is that the infection is actually not in the dermal layer but the fungus actually invades the hair shaft itself.

12:57 Now this condition occurs more commonly more in boys than girls and its most commonly caused by the fungi Tricopython and Microsporum.

13:06 Now, transmission here occurs through contact with other infected humans animals or objects.

13:14 Now what’s quite interesting is that not everyone is symptomatic.

13:18 If you were to sample many people, many people may actually have this fungus in their actual scalp but only some people present with the symptomatic tinea capitis.

13:30 Now what ends up happening is people predominantly who developed this condition are prepubescent so it’s mainly in children, it’s not common in adulthood, so the image I have in my head of tinea capitis is a bunch of young boys wrestling around contacting heads and then having poor hygiene and never really taking care of themselves and getting exposed in developing tinea capitis.

13:54 Now the diagnosis here can absolutely be clinical.

13:57 You can get a history and see the findings and say that’s tinea capitis but to really give the best diagnosis this can be a common board question, what’s the best way to diagnose this condition is that you can have microscopic examination and even microbial cultures.

14:13 Now, another really hot board question topic is alopecia areata.

14:19 For some reason the boards love this.

14:22 You won’t see it too common in practice but the boards just love to ask about this condition.

14:26 Now, Alopecia areata is hair loss in isolated sites of the body most commonly you will see it in the scalp but really, any part of the body can be affected.

14:37 And what it looks like is just simply ball of patches where there was hair without any skins changes; no redness, no swelling, no erythema just simply like the hair was shaved away and you don’t know where it went.

14:51 Now, what’s thought to be the underlying cause of this condition is actually autoimmune in nature where it’s thought you have immune mediated destruction of the hair follicles.

15:02 Now here, unfortunately, there really is no cure available, but you can actually induce hair growth by giving cortisone injections.

15:13 Baricitinib is a recently approved medication for the treatment of severe alopecia areata.