Do Brown Lesions On The Back And Shoulders Indicative Of Becker's Nevus?

Question: Hello! This question pertains to my son, who is 19 years old, and a pigmented lesion he has on his upper back. I had taken him a few months ago to a dermatologist, and the physicians assistant who examined him with a dermascope diagnosed it as a linear epidermal nevus, with little to zero chance of ever becoming dangerous.

I previously posed a question here relating to syndromes linked to epidermal nevi, which I unfortunately ran across while googling, and made me quite anxious. He is healthy and has no diagnosed medical issues.

I am sorry I am not attaching a picture of the lesion, as I simply do not want to ask him to let me take a picture, and think I am doubting or worrying over the diagnosis.

My question now is whether perhaps it more adequately fits the description of a Becker's nevus. The lesion first appeared when he was approximately 12 years old. It is located on the upper back of his left shoulder and is about 3/4 of an inch in size. It first appeared as flat brown patches grouped together, resembling a cafe au lait spot, but as he's gone through puberty it has darkened and perhaps become thicker; it is irregular in shape and there is no hair growing from it. I also recalled that his paternal grandfather (age 85) has a similar spot in the same location, although it is larger, perhaps three inches.

Just wondering if you can offer any insights into whether, due to the location, his gender, an age of onset, it may more likely be a Becker's nevus? Thank you!!!

Hello again Dr. Sawhney! Thank you once again for being there for me with my heuristic questions! I think I am going to put a call into the derms office where I brought him to get more definitive answers on what they saw and diagnosed!

But one last question....if it is just a regular and solitary, small linear epidermal nevus, is it possible for those to develop around the time of puberty? From my neurotic googling of these things, I thought that it has something to do with mutation in the ectoderm(?) and that it would typically be present at birth or shortly thereafter.

Thanks again for your kindness (you will be able to author a book about your online practice and feature me in an entire chapter of the most neurotic questions!!)

Thanks for the information! And I promise, this is my absolute last question (I think I'm eitherbabfruatrated medical student or was a doctor in a former life!).

If it's a regular solitary and small epidermal nevus that deceloped during puberty, does that most likely further substantiate that it's not related to those crazy rare syndromes I had asked you about, and also that it was probably just a sporadic mutation in that small area of skin cells, rather than that than rare (epidermolytic?) type that can cause ichythosis (?) in offspring?

I promise that's the last one Dr. Sawhney! Thanks again for you compassion, kindness and understanding...you've helped me with my health anxiety more than words can say!!