Case Number : Case 2297 - 3 April 2019 Posted By: Dr. Hafeez Diwan

Considering her age,  it could be idiopathic guttate hypomelanosis. 

Why not vitiligo?

3 hours ago, vincenzo said:

Why not vitiligo?

Dear Vincenzo, in vitiligo, there is complete loss of melanocytes and the lesion is depigmented (chalk white in colour). Here, in IGH, the lesions are hypopigmented with focal reduction in melanocytes.

Ah Ok, thanks Anil!

Agree with idiopathic guttate hypomelanosis

Yes, agree with the above.  I called it idiopathic guttate hypomelanosis.

I want to make a comment that the presence of melanocytes does not rule out vitiligo. See reference below:

https://www.ncbi.nlm.nih.gov/pubmed/18360112

I also had a case of hypopigment lesion previously biopsied. An outside dermatopathologist did not call it vitiligo because melanocytes were present. But the dermatologist insisted that it was vitiligo so she rebiopsied after some time. I looked at the second biopsy and called it consistent with vitiligo because there were no melanocytes or pigmentation. 

For case 2297 I think there are a few differential diagnoses, including early vitiligo, idiopathic guttate hypomelanosis (usually multiple lesions), post-inflammatory hypopigmentation, nevus depigmentosus (usually congenital and stable). 

I think for hypopigmented lesions it is difficult to make a definitive diagnosis based on histology alone. The density of melanocytes in normal skin also varies widely.

Please correct me if I am wrong. Thanks!

sir, it is clinical call finally

can we just report as epidermal hypomelanosis focal or spotty, clinically correlate, why must we commit diagnosis

Agree, without clinical correlation, I just say Epidermal Hipomelanosis. 

And also agree that some vitiligo (that look clinical as vitiligo) have some melanocytes and that doesn't rule out the diagnosis

Of course early vitiligo will show some melanocytes. It is after all a clinical diagnosis. 

14 hours ago, John Zhang said:

I want to make a comment that the presence of melanocytes does not rule out vitiligo. See reference below:

https://www.ncbi.nlm.nih.gov/pubmed/18360112

I also had a case of hypopigment lesion previously biopsied. An outside dermatopathologist did not call it vitiligo because melanocytes were present. But the dermatologist insisted that it was vitiligo so she rebiopsied after some time. I looked at the second biopsy and called it consistent with vitiligo because there were no melanocytes or pigmentation. 

For case 2297 I think there are a few differential diagnoses, including early vitiligo, idiopathic guttate hypomelanosis (usually multiple lesions), post-inflammatory hypopigmentation, nevus depigmentosus (usually congenital and stable). 

 

I think for hypopigmented lesions it is difficult to make a definitive diagnosis based on histology alone. The density of melanocytes in normal skin also varies widely.

 

Please correct me if I am wrong. Thanks!

Thanks for the many learning points, John. And I overall agree with :" hypopigmented lesions it is difficult to make a definitive diagnosis based on histology alone". 

You are welcome Vincenzo. I try to tell my clinicians: "if the histology is classic I will report that it is compatible with vitiligo, but I can never tell you that it is not early vitiligo."

I really like this discussion and learned a lot. Thank you!