Case Number : Case 2552 - 17 April 2020 Posted By: Dr. Richard Carr

Malignant spindle cell tumors for immunos. Ddx. Desmoplastic melanoma.

Agree. Lymphoid nodular clusters in sclerotic dermis. There is something resembling Rosaj Dorfman Disease in pic 4, also.

S100 should be +ve in both, but SOX10 could be an appropriate immuno for ddx.

slide 2,3 and 5 showing some collagenolytic changes could be granuloma multiforme, but a mitotic activity is seen in image 6

i dont know

On 17/04/2020 at 19:55, Hamad said:

Malignant spindle cell tumors for immunos. Ddx. Desmoplastic melanoma.

Agree, suspicious for spindle cell melanoma.

This case serves to support Phillip Mckee's adage that before every sign out say to yourself "desmoplastic melanoma" (DM). It is a good idea to perform S100 on any odd fibrohistiocytic / inflammatory looking lesions on the head & neck of an older individual. This case actually dates from several years before and there had been a previous lentigo maligna near this lesion. Despite this an otherwise good, but non-dermato-, pathologist possibly unaware of Phillip's adage signed it out as in keeping with lupus tumidus. We received a recent specimen (some 6 years later) that led us to review this biopsy. I'd like to thank Dr Domenico Mesiano for sharing this learning case. I think it also serves to illustrate the DM in it's pure form can be rather indolent. When I looked at the case "blind" I was thinking of morphoea which serves hopefully to illustrate the difficulty and that it's very easy to slip-up with this diagnosis so that clinical information is highly important. The case is quite similar to another one we illustrated on the leg (granuloma annulare-like).

See also Case 2460

Nice! my thought was desmoplastic melanoma too.