Malignant Mucosal Melanoma



Malignant Mucosal Melanoma


Lester D. R. Thompson, MD





Key Facts


Terminology



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


Clinical Issues



  • Anterior nasal septum > maxillary sinus


  • Overall prognosis is poor


Macroscopic Features



  • Most are polypoid


Microscopic Pathology



  • Protean histology, mimic of many other primary tumor types


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


  • Many patterns of growth


  • Variety of cell types can be seen


  • Prominent, irregular, brightly eosinophilic, enlarged nucleoli


  • Intranuclear cytoplasmic inclusions usually present


  • Melanin-containing tumor cells can be seen


Ancillary Tests



  • Positive: S100 protein, HMB-45, Melan-A, microphthalmia transcription factor, tyrosinase, vimentin


Top Differential Diagnoses



  • Olfactory neuroblastoma


  • Sinonasal undifferentiated carcinoma


  • Melanotic neuroectodermal tumor of infancy


  • Rhabdomyosarcoma


  • Lymphoma







Atypical junctional melanocytes are noted within the respiratory epithelium, arranged in a pagetoid spread image. The tumor cells are also present within the stroma.






Hematoxylin & eosin shows a spindled to polygonal population of highly atypical, pigmented neoplastic cells. These changes are characteristic for a pigmented melanoma.


TERMINOLOGY


Abbreviations



  • Malignant mucosal melanoma (MMM)


  • Sinonasal tract and nasopharynx mucosal malignant melanoma (STMMM)


Definitions



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


ETIOLOGY/PATHOGENESIS


Environmental Exposure



  • Formalin


  • Possibly radiation


  • UV exposure


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Rare



      • Represents < 1% of all melanomas


      • < 5% of all sinonasal tract neoplasms


      • 15-20% of all skin melanomas occur in head and neck


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


  • Age



    • Wide range, usually in 5th to 8th decades


  • Gender



    • Equal gender distribution


  • Ethnicity



    • Increased incidence in Japanese patients


Site



  • 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 is next most common site


  • Anterior nasal septum > maxillary sinus


Presentation



  • Nasal obstruction


  • Epistaxis or nasal discharge



    • Melanorrhea: Black-flecked (melanin) discharge


  • Polyp


  • Pain is uncommon


Treatment



  • 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



    • Can be used after surgery



      • In most cases, it is palliative


Prognosis



  • Poor overall


  • 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


IMAGE FINDINGS


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


MACROSCOPIC FEATURES


General Features



  • Most are polypoid


  • White to gray, brown, or black


  • Surface ulceration/erosion is common


Size



  • Range up to 6 cm


  • Mean: 2-3 cm


MICROSCOPIC PATHOLOGY


Histologic Features



  • Protean histology, mimic of many other primary tumor types


  • Junctional activity and epidermal 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



    • Peritheliomatous: Distinctive and unique for STMMM


    • Epithelioid


    • Solid


    • Organoid


    • Sheets


    • Nests


    • Fascicles and interlacing bundles


    • Storiform


    • Meningothelial


    • Hemangiopericytoma-like


    • Papillary


  • 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 and increased


  • 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

Only gold members can continue reading. Log In or Register to continue

Related posts:

  1. Protocol for the Examination of Nasal Cavity and Paranasal Sinus Specimens
  2. Pleomorphic Adenoma
  3. Subacute Granulomatous Thyroiditis (de Quervain)
  4. Protocol for the Examination of Thyroid Gland Specimens

Stay updated, free articles. Join our Telegram channel
Tags:
Jul 7, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Malignant Mucosal Melanoma

Full access? Get Clinical Tree
Get Clinical Tree app for offline access