desmoplastic melanoma


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desmoplastic melanoma

An uncommon melanoma (2% of all melanomas) that may not be recognised as such initially, and thus is often diagnosed at a higher stage. It is usually associated with lentigo maligna, or less commonly with acral melanoma and other melanomas.

Demographics
Male:female ratio, 2:1; more common in head and neck.

Clinical findings
Innocuous clinical presentation in the form of indurated discoid papule, plaque or nodule. Pigmentation is often absent, but lentiginous discolouration adjacent to the nodule may be seen.

DiffDx
Basal cell carcinoma, squamous cell carcinoma, DFSP, dermatofibroma, cysts, indurated scar-like plaques.
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MELANOMA

desmoplastic melanoma

A rare type of malignant melanoma in which the typical melanotic pigmentation may be absent. It often occurs on the head or neck. Microscopically, the tumor cells are spindle-shaped. Local recurrences after surgical excision are common, as are metastases, esp. to the lungs.
illustration
See also: melanoma
References in periodicals archive ?
Desmoplastic melanoma is frequently a consequence of DNA damage to cells exposed to ultraviolet light.
Desmoplastic melanoma (DM) was the least common subtype in HW, Blacks, and API, with the majority of DM cases being diagnosed in NHW.
The pathology unit reported that the tumor represented a second recurrence of the desmoplastic melanoma.
Although sentinel lymph node biopsy (SLNB) is routine in more common forms of cutaneous melanoma, findings from a retrospective case-control study suggest that it's "not really necessary" for desmoplastic melanoma (DM) of the head or neck, said lead investigator Dylan Roden, MD, of the department of otolaryngology, New York University.
Desmoplastic melanoma often lacks melanin and, sometimes, junctional involvement.
404,405) Desmoplastic melanoma shows increased local recurrence rates, compared to other melanoma subtypes.
Immunoprofiles of Similar Spindle Cell Neoplasms Tumor Type Myogenin Desmin SMA SC-RMS ++ ++ +/- Leiomyosarcoma - +/- ++ Low-grade myofibroblastic - +/- + sarcoma Fibrosarcoma - - +/- Malignant peripheral - - - nerve sheath tumor with rhabdomyoblastic differentiation Desmoplastic melanoma - - +/-- Tumor Type H-caldesmon S100 GFAP SC-RMS - - - Leiomyosarcoma +/- - +/-- Low-grade myofibroblastic - - - sarcoma Fibrosarcoma - - +/- Malignant peripheral - +/- - nerve sheath tumor with rhabdomyoblastic differentiation Desmoplastic melanoma - ++ +/- Abbreviations: GFAP, glial fibrillary acidic protein; SC-RMS, spindle cell rhabdomyosarcoma; SMA, smooth muscle actin; +, positive; ++, strongly positive; +/-, occasionally positive; +/--, occasionally positive, more often negative; -, negative.
16) The Abbott Molecular melanoma FISH test was also validated in critical differential diagnoses concerning histologically unequivocal benign and malignant blue nevi, nevoid melanoma, dysplastic nevi, desmoplastic melanoma, lentiginous melanoma, nevi with atypical epithelioid cell component, and Spitz nevi.
9,10) Chen et al (11) generated a monoclonal antibody against Melan-A in 1996, which is a relatively sensitive and specific marker for benign and malignant melanocytes, except those of desmoplastic melanomas.
Moreover, in cases of pure desmoplastic melanoma (defined as having greater than 90% desmoplastic component), there is a lower incidence of lymph node metastasis and, in many practices, sentinel lymph node biopsy is not recommended.
7) Conversely, strong and diffuse expression of this marker in a spindle cell melanocytic lesion makes a diagnosis of desmoplastic melanoma unlikely.