Quiz 49: What is your diagnosis?

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Diagnosis: Quiz 49

Quiz 49

Answer: Melanocytic nevus, congenital

Criteria for diagnosis clinically: A smooth-surfaced, skin-colored papule is consonant with one type of melanocytic nevus.

Differential diagnosis clinically: This could be an expression, muted, of a fibroepithelial polyp or even of a benign adnexal neoplasm. Biopsy is necessary to establish a diagnosis with surety.

Criteria for diagnosis histopathologically: In the papillary dermis and in the upper part of the reticular dermis, the nests, cords, and strands of abnormal monomorphic melanocytes are those of a melanocytic nevus. Because the process clearly involves at least the upper part of the reticular dermis, this lesion qualifies as one type of congenital nevus.

Differential diagnosis histopathologically: There is none.

Clinicopathologic correlation: The papule came into being because of the proliferation of abnormal melanocytes of the nevus, it is the color of normal skin because there is no increase in the amount of melanin either in the epidermis or the dermis, and the surface is smooth because the stratum corneum is normal.

Options for therapy predicated on knowledge of histopathologic findings: This lesion is benign and, therefore, no additional treatment is indicated.

1) Because the papule was removed by superficial shave technique, no judgment can be made about the extent of involvement of the reticular dermis by the abnormal melanocytes of the nevus. On the basis of what is seen in these sections, however, the findings can be said to fulfill criteria for a congenital nevus. No definitive judgment can be made about the precise type of congenital nevus without benefit the reticular dermis being assessed in its entirety.

2) It may be that this particular kind of nevus has not yet been named. It does not qualify as an Unna's nevus because it is not sufficiently exophytic. It could be a Zitelli's nevus (superficial and "deep" congenital). Many types of melanocytic nevi, however, have yet to be characterized precisely on the basis of correlation clinicopathologic. Although that has been accomplished largely for those melanocytic nevi that have been given designations eponymic, such as Unna's, Miescher's, Spitz's, Clark's, Reed's, Masson's, Ackerman's, Zitelli's, etc., likely it is that many types of equally distinctive melanocytic nevi have yet to be identified on the basis of attributes clinical wedded to those histopathologic.

3) If a swath is ever to be cut through the subject of melanocytic nevi, toward the end of establishing the character morphologic of all of the different types of them (both ones "congenital" and ones "acquired"), it will necessitate photographing each presumed melanocytic nevus prior to biopsy of it, by either punch technique or scalpel excision, followed by correlation clinicopathologic undertaken on a sufficiently large number of nevi to establish with repeatability the individuality of each type of them.

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