A firm lesion on the right arm. Leave it or not? Why or why not?

A case by Keir Jeffrey

Age 54 years; Sex: female; Location: upper limb

Clinical: a palpably firm lesion on the right upper arm

answers (conclusion):

Sergeev Yury (5/11/2016 11:29:39 AM): Looks like a DF, but like a strange one – off

Baker Ron (5/11/2016 12:54:20 PM): You clearly cannot leave it, way too much chaos. For me this lesion has a chaotic distribution of multiple colours including grey, white, pink, various shades of brown, and some black. It also has a relatively chaotic distribution of structures including dots and globules, structureless areas, and radial streaming. There is a negative network.

For all those reasons it must be excised to exclude melanoma, though it is not guaranteed to be melanocytic. DDX looks a bit wide, including Bowen’s, a DF, a Seb K, even a pBCC.

The only certainty is that it needs bottling. Thanks for a tricky case.

Keir Jeffrey (5/11/2016 1:55:43 PM): It was very firm, Ron – and dimpled to palpation.

Maggoschitz Iryna (5/11/2016 2:26:49 PM): Clinicaly (firm) and macrocopic-typical DF. Dermatoscopic radial brown lines at the periphery (rare but typical for DF), also white lines at the centre ist typical for DF. The Lesion is symmetrical,but there are brown and grey dots and Brown globules in the lesion (not typical for DF), therefore i would excise.

Inskip Michael (5/11/2016 2:27:59 PM): Probably a pigmented dermatofibroma. Possibly a melanoma. Excise.

Baker Ron (5/12/2016 6:05:31 AM): So you are saying Jeff that clinically it was a classic DF. I see DFs every day, but probably only get histology on 1 or 2 a year. This one needs histology to my eyes….and I note everyone else agrees. Sometimes the clinical trumps the dermoscopy but I don’t see how you can accept the dermoscopy in this case as safe. I assume you excised it.

Inskip Michael (5/12/2016 12:00:06 PM): The inverse pigment network in this lesion could indicate dermatofibroma or melanoma.

However the degree of chaos, the peripheral brown dots & multiple colours are just not consistent with.dermatofibroma. Nodular, necrotic melanomas can be firm & dimple. This is a melanoma.

Keir Jeffrey (5/12/2016 3:11:55 PM): It could have been mistaken for a DF without dermatoscopy. But not typical as you have pointed out. Chaos because of asymmetry of colour. Clues of lines peripheral radial segmental + grey.

Desmoplastic melanoma, Breslow 2.5mm

Inskip Michael (5/12/2016 3:58:57 PM): Desmoplastic melanoma can unfortunately be a lot more bland looking than this and very tricky indeed to pick up.

Inskip Michael (5/12/2016 4:04:21 PM): There’s a picture of a desmoplastic melanoma with similar inverse pigment network in this study.

Jaimes N, Chen L, Dusza SW, Carrera C, Puig S, Thomas L, Kelly JW, Dang L, Zalaudek I, Braun RP, Menzies SW, Busam KJ, Marghoob AA.

Clinical and dermoscopic characteristics of desmoplastic melanomas.

JAMA Dermatol. 2013 Apr;149(4):413-21

Baker Ron (5/14/2016 12:42:23 AM): Thanks for the case.