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In this section we have spot diagnoses posted on a daily basis since June 2010, now over 1700! You can review the archived cases and read the suggested diagnoses by users and the final comment by Dr Uma Sundram, the Editor-in-Chief and main spot diagnosis host. Case are uploaded each week day by 10 a.m. UK time with the correct diagnosis will generally be posted at 8 p.m. UK time. Why not view the most recent spot diagnosis and proffer a diagnosis?

Case Number : Case 838 - 3rd September Posted By: Guest

Please read the clinical history and view the images by clicking on them before you proffer your diagnosis.
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The patient is a 75 year old woman with an excision of a pigmented macule from the left arm.

Case posted by Dr. Mark Hurt.


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Guest Maria George

Posted

I shall give her the benefit of doubt.Malignant melanoma insitu.

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Guest Maria George

Posted

I shall give her the benefit of doubt.Malignant melanoma insitu.

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Arti Bakshi

Posted

agree with large cell acanthoma.
image labelled as 'transition zone' is instructive!

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Robledo F. Rocha

Posted

Large cell acanthoma. A circumscribed area of epidermis with enlarged keratinocytes topped by hyperorthokeratosis. Like Dr. Bakshi, I found the transition zone very instructive.

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Guest Jim Davie MD

Posted

- Large cell acanthoma (pigmented variant).

[size=4] Nuclear and cytoplasmic enlargement of keratinocytes (maintaining similar nuclear/cytoplasmic ratio as normal keratinocytes), hypergranulosis, and hyperorthokeratosis.
Seeing a clonal proliferation of enlarged keratinocytes--well-demarcated against normal, smaller keratinocytes, as seen in the 'transition zone' photo above--with involvement of the basal keratinocytes, is helpful in differentiating it from simple reactive keratinocytes, which may result from chronic inflammation and/or irritation. When there is actinic dysplasia, the differential would then include actinic keratosis.
[MelanA and Ki67 stains show expected basal melanocytes, which are dwarfed by the surrounding enlarged keratinocytes, and absence of high-level scatter or high-level proliferative activity].[/size]

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Mark A. Hurt MD

Posted

My diagnosis was: Large Cell Acanthoma.

Some refer to these as solar lentigines, but I usually reserve that name for lesions in which the retia are hyperpigmented and elongated ("dirty" feet). I see these lesions frequently in my practice, and usually the diagnosis clinically is melanoma in situ. The photographs above are stereotyped for the melanocytic density in these lesions, and, as Jim stated, there is no "high-level scatter" of Ki-67 in the keratocytes. As a rule, melanoma in situ should have more confluence of melanocytes at the DE junction.

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Dr. Richard Carr

Posted

Agree with the "academic" diagnosis but the distinction seems to be rather academic from a relatively flat solar lentigo which, afterall, is probably just a thin seborrhoeic keratosis! For the clinicians (even most dermatologists are not over familiar with this diagnostic splitting) I like not to confuse them with some of our more "academic" diagnoses so I might label it "solar lentigo / thin seborrhoeic keratosis (so-called large cell acanthoma variant)".

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Mark A. Hurt MD

Posted

Richard, your viewpoint is similar to that of Roewert & Ackerman in 1992 (http://www.ncbi.nlm.nih.gov/pubmed/1533104). In that back and forth, there were opposing viewpoints (http://www.ncbi.nlm.nih.gov/pubmed/1348913), but I have, more or less, come to agree with Roewert & Ackerman's position on the lesions. Oddly enough, some years ago, I tended to place them in the category of solar keratosis, which I hold is in the spectrum SCCIS, but clinicians kept telling me that LCA's did not respond to 5FU, which indicated to me that their biology seems not to be like a solar keratosis. I think there is a group of lesions with features similar to LCA and which contain nuclear pleomorphism in full thickness but cornify via compact orthokeratosis. I think this is a special class of SCCIS, but it is relatively uncommon.

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