The term desmoplasia refers to connective tissue proliferation and, when applied to malignant melanoma, describes different clinical presentations; however, each has a similar microscopic pathology characterized by (1) a dermal fibroblastic component of melanoma with only minimal or absent melanocytic proliferation at the dermal-epidermal junction, (2) nerve-centered superficial malignant melanoma with or without an atypical intraepidermal melanocytic component, or (3) other lesions in which the tumor appears to arise in lentigo maligna or, rarely, in acral lentiginous melanoma or superficial spreading melanoma. Also, desmoplastic melanoma (DM) growth patterns have been noted in recurrent malignant melanoma. The primary tumors occur on the head and neck, most commonly on the face, but may be first noted on the trunk or extremities. DM occurs more frequently in women and in persons with dermatoheliosis (“photoaging”). The diagnosis requires an experienced dermatopathologist; S-100 immunoperoxidase-positive spindle cells need to be identified in the matrix collagen. HMB-45 staining may be negative.
Causes of Desmoplastic Melanoma
DM may be a variant of lentigo maligna melanoma in that most lesions occur on the head and neck in patients with sun-damaged skin. DM is more likely to recur locally and metastasize than lentigo maligna melanoma, however.
Symptoms of Desmoplastic Melanoma
Early signs of melanoma include ABCDEs: asymmetry of lesion; border irregularity, bleeding, or crusting; color change or variegation (some lesions are amelanotic—non-pigmented); diameter over 6 mm or growing lesion; elevated area (or palpable papule) in a previously flat nevus.
Diagnosis
It is essential to obtain an adequate biopsy; punch biopsies can be misleading.
Treatment
Desmoplastic melanoma is thought to have a high likelihood of local recurrence (recurrence at or near the site of the original melanoma), prompting some to suggest treatment with radiation therapy as well as surgery. Given the side-effects and cost of radiation therapy, however, it is important to determine whether the addition of radiation therapy is likely to have a benefit.
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