Home Chapter Home Jobs Conferences Fellowships Books
Skin-Melanocytic Tumors
Last major update: November 2008 - next update November 2009
Revised: 16 October 2009
Author: Nat Pernick, M.D., PathologyOutlines.com, Inc.
Copyright: (c) 2002-2009, PathologyOutlines.com, Inc.
Definition
=========================================================================
● Rare variant of spindle cell melanoma seen in older adults in sun-exposed skin
● A type of nodular (vertical growth) melanoma with scanty spindle cells, prominent desmoplastic stroma and often minimal atypia
● First described in 1971 (Cancer 1971;28:914)
Terminology
=========================================================================
● Also called desmoplastic neurotropic melanoma if neuroma-type features with prominent nerve involvement (Adv Anat Pathol 2005;12:92)
Clinical
=========================================================================
● Mean age 71 years, 72% in head, often nonpigmented
● Commonly misdiagnosed; only 27% are initially diagnosed as melanoma (Am J Dermatopathol 2008;30:207)
● 76% survival at 5 years (Ann Surg Oncol 2006;13:728), may be similar to melanomas with similar thickness (J Clin Oncol 2005;23:6739), although have fewer positive sentinel lymph nodes than classic melanoma (Cutis 2007;79:390, Cancer 2006;106:900)
Case reports
=========================================================================
● Young woman with scalp cyst (Univ of Pittsburgh Case #378)
● 81 year old man with scalp lesion (The Internet Journal of Dermatology 2008;6(2))
● Collision tumor with squamous cell carcinoma on lip (J Cutan Pathol 2008;35:473)
● Osteogenic tumor of foot (J Cutan Pathol 2007;34:423)
Treatment and prognosis
=========================================================================
● Wide local excision with careful attention to margins (Cancer 2005;104:1462)
● May recur if positive margins (Cancer 2008;113:2770)
● Possibly adjuvant radiotherapy to reduce recurrence (ANZ J Surg 2008;78:273)
● Poor prognostic factors are mixed subtype (AJSP 2004;28:1518, Ann Surg Oncol 2005;12:207) and possibly N-cadherin expression (Hum Path 2006;37:899)
Clinical description
=========================================================================
● Often nonpigmented and mistaken for nonmelanocytic lesion, such as scar
● Usually advanced thickness at presentation (Br J Dermatol 2005;152:673)
Clinical images
=========================================================================
2.5 cm scalp lesion
Dermoscopy
=========================================================================
● Features of regression (white scar like areas, peppering)
● Also multiple colors, linear irregular vessels or milky-red areas (Br J Dermatol 2008;159:360)
Micro description
=========================================================================
● Poorly circumscribed; focal fascicular pattern of scanty spindle cells with prominent desmoplastic stroma
● Tumor cells may have minimal atypia
● Solar elastosis (82%), amelanotic (71%), deep invasion, perineural infiltration (35%), lymphoid aggregates at periphery (37%), may grow in peripheral nerve sheath pattern
● May be pure or combined with classic melanoma (pure have better prognosis, Am J Surg Pathol 2004;28:1518)
● In about 15% of case there is no evidence of an intraepidermal melanocytic component
Micro images
=========================================================================
Dense eosinophilic fibrous stroma Mixed with classic melanoma
with hypocellular spindle cells
Desmoplastic versus
non-desmoplastic melanoma
81 year old man with scalp lesion
Various images
Strong S100 staining S100 and T311 (tyrosinase)
Tyrosinase
Cytology description
=========================================================================
● Clean background; aggregates of pleomorphic spindle cells mixed with fibrous stroma and single cells
● Fine, wispy and delicate cytoplasm at nuclear poles, nuclei are elongated and plump with irregular contours, deep grooves and folds, dark coarse chromatin with variably prominent nucleoli (Cytojournal 2007;4:18)
● Compared to other melanomas, is less cellular and less often has intranuclear cytoplasmic inclusions and mitotic figures (Am J Clin Pathol 2008;130:715)
Cytology images
=========================================================================
Various images
Positive stains
=========================================================================
● S100 (strong, Melanoma Res 2006;16:347)
● May have high Ki-67 index
● Possibly NGFR (Am J Dermatopathol 2006;28:162)
● KBA.62 (Hum Path 2008;39:1136)
● Clusterin (J Invest Dermatol 2005;124:412)
Negative stains
=========================================================================
● HMB45 and MelanA (usually, but may have focal staining of epithelial cells in junctional component or superficial dermis, Am J Dermatopathol 2004;26:452)
● MITF (usually, Am J Dermatopathol 2001;23:185, Am J Surg Pathol 2002;26:82)
● Tyrosinase (usually)
Molecular / cytogenetics
=========================================================================
● V599E BRAF mutation not present (Cancer 2005;103:788)
Differential Diagnoses
=========================================================================
● Hypertrophic scar
● Sclerotic or nonpigmented blue nevi (strongly MelanA+, Am J Dermatopathol 2004;26:452)
● Atypical fibroxanthoma
● Spindle squamous cell carcinoma
● Peripheral nerve sheath tumor (usually S100A1 negative, J Cutan Pathol 2008;35:1014)
● Neurofibroma
● Fibromatosis
● Basal cell carcinoma
End of Skin-Melanocytic Tumors > Desmoplastic melanoma
This information is intended for physicians and related personnel, who understand that medical information is often imperfect, and must also be interpreted in the context of a patient's clinical data using reasonable medical judgment. This website should not be used as a substitute for the advice of a licensed physician.
All information on this website is protected by Copyright, (c) 2001-2009, PathologyOutlines.com, Inc. Information from third parties may also be protected by copyright. Please contact us at copyrightPathOut@gmail.com with any questions.