Sinonasal Melanoma

Sinonasal Melanoma

Lester D. R. Thompson, MD

Isolated junctional neoplastic cells are noted image in this MMM. The neoplastic cells in the stroma show pleomorphism and a plasmacytoid appearance. Pigment is easily identified.

High magnification shows a spindled to polygonal population of highly atypical, pigmented neoplastic cells. These changes are characteristic of melanoma.



  • Mucosal malignant melanoma (MMM)

  • Sinonasal tract mucosal malignant melanoma (STMMM)


  • Neural crest-derived neoplasms originating from melanocytes and demonstrating melanocytic differentiation


Environmental Exposure

  • Formalin

  • Possibly radiation

  • UV exposure



  • Incidence

    • Rare

      • Represents < 1% of all melanomas

      • < 5% of all sinonasal tract neoplasms

      • 15-33% of all skin melanomas occur in head and neck

      • STMMM represent < 4% of all head and neck melanomas

  • Age

    • Wide age range, usually in 5th-8th decades

  • Gender

    • Equal gender distribution

  • Ethnicity

    • Increased incidence in Japanese patients


  • About 15-20% of melanomas arise in head and neck

    • 80% are cutaneous in origin

    • Ocular origin account for majority of remaining MMM

    • Sinonasal tract and oral cavity are next most common sites

  • Anterior nasal septum > maxillary sinus


  • Nasal obstruction

  • Epistaxis or nasal discharge

    • Melanorrhea: Black-flecked (melanin) discharge

  • Polyp

  • Pain is uncommon


  • Options, risks, complications

    • Metastatic melanoma to sinonasal tract can develop but is vanishingly rare

    • Breslow thickness and Clark level are not used in sinonasal tract

  • Surgical approaches

    • Wide local excision is treatment of choice

  • Radiation

    • Radiation can be used after surgery

      • In most cases, it is palliative


  • Overall prognosis is poor

  • 5-year survival: 17-47%

  • Recurrences are common

  • Poor prognosis associated with

    • Obstruction as presenting symptom

    • Nasopharynx or “mixed site” of involvement

    • Tumor ≥ 3 cm

    • Undifferentiated histology

    • High mitotic count

    • Recurrence

    • Stage of tumor

  • Matrix metalloproteinases (MMPs: Proteolytic enzymes required for extracellular matrix degradation) expression may be associated with patient outcome

    • Decreased MMP2 expression associated with greater overall survival

    • Positive MMP14 expression associated with poor survival


Radiographic Findings

  • Usually identifies extent of tumor and bone invasion

  • Positron emission tomography (PET) tends to show posterior nasal cavity and sinus tumors better than anterior nasal tumors

  • Locoregional and metastatic disease can be detected


General Features

  • Most are polypoid

  • White to gray, brown, or black

  • Surface ulceration/erosion is common


  • Range up to 6 cm

  • Mean: 2-3 cm


Histologic Features

  • Protean histology, mimic of many other primary tumor types

  • Junctional activity and intraepidermal migration (Pagetoid spread) help to confirm primary tumor

  • Surface ulceration is common, obscuring “in situ” component

  • Bone or soft tissue invasion is common

  • Many patterns of growth

    • Nests

    • Solid

    • Organoid

    • Sheets

    • Fascicles and interlacing bundles

    • Storiform

    • Meningothelial

    • Papillary

    • Hemangiopericytoma-like

    • Peritheliomatous: Distinctive and unique for STMMM

  • Variety of cell types can be seen

    • Undifferentiated

    • Epithelioid, polygonal

    • Small cell

    • Plasmacytoid

    • Rhabdoid

    • Giant cell

  • Vesicular nuclei, although sometimes hyperchromatic

  • Prominent, irregular, brightly eosinophilic, enlarged nucleoli

  • Intranuclear cytoplasmic inclusions usually present

  • Melanin-containing tumor cells can be seen

  • Tumor cell necrosis is common

  • Mitotic figures, including atypical forms, usually easily found

  • Inflammation may be present, but not of consequence

  • Desmoplastic type fibrosis can be seen, but is not common

  • Perineural invasion, when present, is poor prognostic indicator

  • Tumor depth of invasion (Clark) impossible to accurately assess

  • Tumor thickness (Breslow) not meaningful in sinonasal tract

Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Sinonasal Melanoma
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