Underground mole? Skin cancer?

I just recently discovered that there was a mole-looking thing on the back of my hand. It looks like a mole in that it's small and round. However, it has more of a blue-ish green color when looked at closely, and instead of being out on the top layer of the skin, it appears to be several layers under the skin, like a bruised follicle or something.





What is this?
Underground mole? Skin cancer?
Melanocytic nevi are benign neoplasms or hamartomas composed of melanocytes, the pigment-producing cells that constitutively colonize the epidermis. Melanocytes are derived from the neural crest and migrate during embryogenesis to selected ectodermal sites (primarily the skin and the CNS), but also to the eyes and the ears. Ectopic melanocytes have been identified at autopsy in the gastrointestinal and genitourinary tracts.





Melanocytic nevi are completely benign. However, melanocytic nevi can be found in association with melanoma. The true frequency of transformation of a melanocytic nevus into melanoma is not known, and the estimated prevalence varies widely in published series. In some series, it is quite low, while in others, it is up to 40%. Both acquired and congenital melanocytic nevi hold some risk for the development of melanoma. Congenital nevi hold the greater risk.





Large and giant congenital melanocytic nevi often have both biological and cosmetic implications. Large congenital nevi have a low but real risk for malignant transformation and the development of melanoma. Some authorities believe that melanoma can develop within a giant congenital nevus in up to 5% of cases.


Melanocytic nevi are common lesions that can be found on the integument of almost all individuals. Some patients present with few lesions, while others have hundreds. The number on a given individual increases in rough proportion to the degree of skin pigmentation.





Nevi can be broadly divided into congenital and acquired types. Determining if a lesion is congenital or acquired is generally easily accomplished by direct query of the patient, although some small congenital melanocytic nevi are tardive and may be perceived by the patient as acquired.





When evaluating the nature of a melanocytic lesion, a number of attributes must be assessed. Further commentary describing physical attributes can be found in Physical.


Whether a lesion has become symptomatic (eg, itchy, painful, irritated, or bleeding) is important.





Not all melanocytic nevi that change are malignant, especially if change is noted in a person younger than 40 years. However, change that is perceptible over a short time is an indicator of potential malignancy and designates a lesion deserving of biopsy.


Acquired melanocytic nevi are typically less than a centimeter in diameter and evenly colored.


Melanocytic nevi most commonly are tan to brown, but coloration can be variable, ranging from skin-colored (nonpigmented) to jet black.


Spitz nevi are a distinctive variant of melanocytic nevi. In decades past, these lesions were called juvenile melanomas, but now they are recognized by specific microscopical features and are known to be benign. The outdated designation juvenile melanoma persists in some areas, but the term should be discarded because of the dire prognosis it suggests and its potential for misconstrued implications.


Although Spitz nevi tend to manifest as pink papules on the head of a child, they can be clinically indistinguishable from conventional nevi in some instances; they also can be heavily pigmented.





Many Spitz nevi exhibit considerable associated vascular ectasia and, thus, display a hemangiomalike clinical appearance.


Blue nevi are a form of melanocytic nevi that typically is heavily pigmented. Because of the presence of deep pigmentation within a refracting colloidal medium (namely, the skin), the brownish-black pigment present contributes a bluish cast to such lesions, thereby explaining the name. The optical effect that accounts for clinical blueness is known as the Tyndall phenomenon.


Not all blue nevi are blue, and some are various shades of gray, brown, or black. The clinical appearance varies depending on the degree of clinical pigmentation. Indeed, some blue nevi may be wholly amelanotic. Because of the fact that the term blue nevus is not always reflective of the true clinical appearance of the lesion, some dermatopathologists name blue nevi based on the cellular morphology present (eg, dendritic melanocytic nevi).


Despite their variability in coloration, blue nevi are usually relatively small and reasonably symmetric, as typically is the case in benign lesions. Blue nevi typically occur on the distal extremities or scalp, but they can occur anywhereSimple excisional biopsy is the procedure of choice for removal and diagnosis of a melanocytic nevus. All removed melanocytic nevi should be submitted for microscopic evaluation. Because the interpretation of pigmented lesions may be challenging, many dermatologists prefer to have their specimens read by a qualified dermatopathologist.


Either shave biopsy or punch biopsy is typically used for cosmetic removal of banal melanocytic nevi.


Strive for complete excision of the lesion, if at all possible, when a melanocytic nevus is removed for diagnosis because of its atypical features (with the ultimate goal of excluding the possibility of melanoma from the differential diagnosis).


A complete excisional biopsy permits all available histopathological criteria to be applied to a lesion and thus enables a more precise diagnosis.


When a partial punch or shave biopsy sample is taken from a lesion, the interpreting pathologist cannot apply important criteria, such as symmetry and circumscription (lateral demarcation), to the assessment of the lesion. If a partial biopsy specimen of a larger lesion is obtained because of clinical necessity, the fact that the specimen is partial should be clearly indicated on the requisition form.


Partial biopsy samples can sometimes lead to misdiagnosis because of sampling error.


Partial biopsy samples can inflate the number of procedures required for diagnosis because a partial biopsy sample that does not enable a definitive diagnosis to be made necessarily leads to subsequent reexcision of the lesion in question.