Melanoma, Nodular Type


Crusted Scalp Tumor
The tumor image is crusted on the scalp of this elderly man. The skin-colored nodule on the left image is benign, either a neurofibroma or a neurotized intradermal nevus. (Courtesy J. Finch, MD.)



image
MM-NT
This lesion was located on the posterior neck of a middle-aged man. Although it has a stuck-on appearance, it has uneven, jagged edges image. The biopsy showed melanoma, nodular type (MM-NT). (Courtesy J. Finch, MD.)

image
MM-NT With Collarette Formation
Low-power examination of a melanoma, nodular type shows a large, expansile dermal nodule with irregular pigmentation image and areas of epidermal thinning and necrosis image (but no complete ulceration in this section). There is collarette formation image and no radial growth phase.

image
MM-NT at Higher Magnification
There is proliferation of melanoma cells in nests and nodules. There is significant nuclear pleomorphism and hyperchromasia image. Mitotic figures image are easily found.


TERMINOLOGY


Abbreviations




• Melanoma, nodular type (MM-NT)


Definitions




• Invasive melanoma that histologically lacks radial growth phase
image Radial growth phase is defined by prominent junctional component


CLINICAL ISSUES


Epidemiology




• Incidence
image 2nd most common subtype of invasive melanoma (after superficial spreading type)

• Age
image Median age of onset: 49 years


Site




• Typically on backs of males and legs of females
• Usually found in sun-exposed areas

image Much less common in areas without sun exposure


Presentation




• Raised, firm, dome-shaped mass of varied color
image May be black, reddish, partially pigmented, or even achromatic

image May have unequal color distribution or be homogeneous in color

image Dominant color is black, with brown being 2nd most common color

• Usually symmetrically shaped

• Ulceration and bleeding commonly occur


Natural History




• May grow very quickly
image Are commonly relatively new-onset lesions that lack radial growth phase

• More commonly are deeply invasive than other types of melanoma


Prognosis




• Depends on depth of invasion (Breslow depth), ulceration, and mitotic index
• Lymphatic invasion and lymph node metastasis are significant poor prognostic indicators

image Median survival with metastasis: 4.4 months

• Lead to poor prognosis in most cases
image Considerable Breslow depth

image Lymphovascular invasion

image Early metastases to vital organs

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

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