Desmoplastic Melanoma pathology different?

My husband was diagnosed with Desmoplastic Melanoma (DM) on the crown of his head, which is a rare type that affects anywhere from 1% – 4% of melanomas depending on what you read.  It also frequently recurs locally.  As such, the doctor says that the melanoma does not behave in the same ways as other types.  DM has no color usually, his was just a bump on his head.  As such, it usually goes undiagnosed and can get quite large before it gets recognized.  We thought it was a cyst.

My husband was diagnosed with Desmoplastic Melanoma (DM) on the crown of his head, which is a rare type that affects anywhere from 1% – 4% of melanomas depending on what you read.  It also frequently recurs locally.  As such, the doctor says that the melanoma does not behave in the same ways as other types.  DM has no color usually, his was just a bump on his head.  As such, it usually goes undiagnosed and can get quite large before it gets recognized.  We thought it was a cyst.

He had surgery 2 weeks ago to remove 2 cm margin around the site, replacing the tissue with a skin graft.  They did not do lymph node biopsy because of the location of the lymph nodes, and the percentage of lymph node involvement with DM is only 7% usually.   We got the pathology report back.  The margins were clear, but I'm concerned about the other things I'm reading in the path report.  When I look them up on the internet, most of the features look very negative.  The doctor says that DM doesn't follow the normal course, and I hope he's right.  Anyone know about this?  

Here are the results:

Top of scalp, excision:

Histologic type:  Malignant melanoma, desmoplastic type, sectional edges involved comment.

Clark's level:  V

Breslow depth:  At least 0.5 cm

Vertical growth phase:  Present

Ulceration:  Absent.

Lymphovascular invasion:  Absent.

Perineural invasion:  Present

Tumor infiltrating lymphocytes:  Not brisk.

Regression:  Absent

Mitotic figures:  Up to 5 per mm squared

Tumor micros-satellites:  Absent

Precursor lesions:  Absent

"The lesion extends to and involves the deep inked margin and is <1 mm from the 12 o'clock inked margin.  The 3, 6, and 9 o'clock margins appear clear by >1.0 cm.  The separately submitted en face margins show multiple foci of atypical intraepidermal melanocytic proliferation which may represent a field effect phenomenon."

Pathologic stage:  pT4a, pNX, pMX