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NBME 23 Answers

nbme23/Block 2/Question#13

A 45-year-old man comes to the office for a health ...

Invasion of the submucosa

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 +2  upvote downvote
submitted by joker4eva76(9),

This is representative of leukoplakia, a pre-cancerous lesion of squamous cells. In order for it to spread to distant sites, it must first invade through the basement membrane/submucosa. Could be confused with oral hairy leukoplakia (which also is a white patch that classically arises on the lateral tongue). However, oral hairy leukoplakia is not pre-cancerous and is often associated with EBV infections or people that are severely immunocompromised.

hpkrazydesi  How did you know that this wasnt oral hairy leukoplakia? just from the picture? +1  
nwinkelmann  To piggyback off of @hpkrazydesi, you ruled out oral hairy leukoplakia because the patient was seeing the doctor for normal health maintenance, i.e. not immunocompromised, I'm assuming. +1  
dentist  @nwinkelmann thats correct! my time to shine. +  

 +0  upvote downvote
submitted by nwinkelmann(57),


Leukoplakia = risk factors include male gender, 40-70 years old, smoking, White patch or plaque, 5 mm or more, on oral mucous membranes that cannot be removed by scraping, not due to another disease entity such as lichen planus or candidiasis and not reversed by removal of irritants and lesion must be considered precancerous until proven otherwise. Premalignant lesion transformation would lead to invasion of the submucosa.

Micro = Varies histologically from acanthosis, hyperkeratosis, dysplasia or carcinoma in situ (associated with lymphocytes and macrophages). This article explains it much better and has pictures: Based on this article and the pictures, I'd say the histo slide in the question is at least moderate squamous dysplasia.

Hairy Leukoplakia = White, confluent patches of fluffy (hairy) mucosa, bilateral, along lateral tongue, and associated with HIV+ patients (AIDS may appear within 2 - 3 years) but actually due to EBV infection

Histo = Hyperkeratotic oral mucosa due to piling of keratotic squamous epithelium, Cowdry type A intranuclear inclusions, Balloon cells with margination of chromatin (nuclear beading); EBV present in clear cells of spinous layer, variable koilocytosis, superimposed Candida infection, without inflammatory response.

From pictures (and this video: timestamp 1:22), hairy leukoplakia has a lightly stained band of cells "ballon cells" in the stratum spinosum which is where the EBV lives. It looks much different than the histo slide shown in the question.

yb_26  great explanation, thanks for sharing! +  
shriya goyal  great explanation thanks +