Sinonasal Melanoma

 Peritheliomatous: Distinctive and unique for sinonasal melanoma



• Variety of cell types can be seen
image Undifferentiated, epithelioid, polygonal, small cell, plasmacytoid, rhabdoid, giant cell

• Prominent, irregular, brightly eosinophilic, enlarged nucleoli

• Intranuclear cytoplasmic inclusions usually present

• Melanin-containing tumor cells can be seen




Ancillary Tests




• Positive: S100, SOX10, HMB-45, Melan-A, tyrosinase, vimentin


Top Differential Diagnoses




• Olfactory neuroblastoma

• Sinonasal undifferentiated carcinoma

• Rhabdomyosarcoma

• Meningioma

• Leiomyosarcoma, biphenotypic sinonasal sarcoma

• Multiple myeloma (sometimes lymphoma)

• Melanotic neuroectodermal tumor of infancy

image
Cartilage Destruction by Melanoma
The nasal septum cartilage image is being destroyed by the infiltrative neoplasm. The tumor forms a thick, sheet-like distribution. No pattern of growth can be seen at this magnification, although ulceration is present.


image
Junctional Melanoma Confirms Primary Melanoma
Neoplastic, atypical junctional melanocytes are noted within the respiratory epithelium, arranged in pagetoid spread image. The tumor cells are also present within the stroma. This change helps to confirm a primary tumor.

image
Spindled Cells in STMMM
The neoplastic cells are arranged in a short fascicular architecture, comprised of spindled cells. Nucleoli are quite prominent.

image
Pigmented STMMM
Hematoxylin and eosin shows a spindled to polygonal population of highly atypical, pigmented neoplastic cells. These changes are characteristic for a pigmented melanoma. The pigment must be within the atypical cells (rather than histiocytes) to qualify as a pigmented melanoma.


TERMINOLOGY


Definitions




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


ETIOLOGY/PATHOGENESIS


Environmental Exposure




• Formalin, possibly radiation, &/or UV exposure


CLINICAL ISSUES


Epidemiology




• Incidence
image Rare

– Represents < 1% of all melanomas

– < 5% of all sinonasal tract neoplasms

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

– Sinonasal tract and nasopharynx mucosal malignant melanoma (STMMM) represent < 4% of all head and neck melanomas

• Age
image Wide range, usually in 5th-8th decades

• Sex
image Equal gender distribution

• Ethnicity
image Increased incidence in Japanese patients


Site




• ~ 15-20% of melanomas arise in head and neck
image 80% are cutaneous in origin

image Ocular origin account for majority of remaining malignant mucosal melanoma (MMM)

image Sinonasal tract is next most common site

• Anterior nasal septum > maxillary sinus


Presentation




• Nasal obstruction
• Epistaxis or nasal discharge

image Melanorrhea: Black-flecked (melanin) discharge

• Polyp

• Pain is uncommon


Treatment




• Options, risks, complications
image Metastatic melanoma to sinonasal tract can develop but is vanishingly rare

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

• Surgical approaches
image Wide local excision is treatment of choice

• Radiation
image Adjuvant postoperative radiation therapy may improve locoregional control but does not affect survival


Prognosis




• Poor overall
• 5-year survival: 17-47%

image 5-year disease-free survival: < 20%

• Recurrences are common

• Poor prognosis associated with
image Obstruction as presenting symptom; nasopharynx or mixed site of involvement; tumor ≥ 3 cm; undifferentiated histology; high mitotic count; recurrence; stage of tumor

• Tyrosine kinase inhibitors may work when protooncogene KIT mutations are detected

• Matrix metalloproteinases (MMPs) (proteolytic enzymes required for extracellular matrix degradation) expression may be associated with patient outcome
image Decreased MMP2 expression associated with greater overall survival

image Positive MMP14 expression associated with poor survival


IMAGING


Radiographic Findings




• Usually identifies extent of tumor and bone invasion

• PET tends to show posterior nasal cavity and sinus tumors better than anterior nasal tumors

• Locoregional and metastatic disease can be detected


MACROSCOPIC


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


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

image Peritheliomatous: Distinctive and unique for STMMM

image Epithelioid, solid, organoid, sheets, nests, papillary structures

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Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Sinonasal Melanoma
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