nodular melanoma

Nodular melanomas have no antecedent radial growth phase. They are therefore nodular, polypoid, or occasionally pedunculated, dark brown or blue-black lesions occurring anywhere on the body.

Occasionally flesh-colored amelanotic variants are found.

They often fail to fulfill the ABCD diagnostic criteria.Ulceration may be present. A giant lesion, 12 cm in width, has been reported.

Microscopy

Nodular melanoma has no adjacent intraepidermal component of atypical melanocytes, although there is usually epidermal invasion by malignant cells directly overlying the dermal mass.

Heenan has challenged the validity of nodular melanoma as a discrete entity.

The dermal component is usually composed of oval to round epithelioid cells but, as in other types of melanoma, this can be quite variable.

They are often thick melanomas. Monster cells are rarely present. Such cases may sometimes resemble an atypical fibroxanthoma.

Mast cells are increased in this and other types of melanoma.

Erythrophagocytosis by tumor cells is an exceedingly rare phenomenon.

Protocols

 CAP protocol, June 2012. Based on AJCC/UICC TNM, 7th edition.