Answer: Miescher's nevus
Criteria for diagnosis clinically: A tan
smooth-surfaced papule on a lip is characteristic of Miescher's
Differential diagnosis clinically: There is
Criteria for diagnosis histopathologically: A
dome-shaped papule composed of nests, cords, and strands of
monomorphic melanocytes that mature with descent progressive in the
dermis is a Miescher's nevus.
Differential diagnosis histopathologically:
There is none.
Clinicopathologic correlation: The papule is
formed of melanocytes of a nevus, and its brown hue is related to
the presence of melanin in the cytoplasm of some of those
melanocytes. The smooth surface cannot be explained by changes
pictured in these photomicrographs because no epidermis is
visualizable, it having been destroyed when the lesion was
desiccated lightly prior to its being biopsied.
Options for therapy predicated on knowledge of
histopathologic findings: Even though this nevus has not
been removed in its entirety (melanocytes of the nevus are present
at the base of the section), no further surgery is necessary
because the lesion is benign.
1) Clinically and histopathologically, the melanocytic condition
shown here fulfills criteria for Miescher's nevus, it being one of
many different types of congenital melanocytic nevus.
2) Many a congenital nevus, including Unna's nevus, some
examples of nevus spilus, and episodically a garment nevus, is not
present at the moment of birth but makes its appearance weeks,
months, and even years later. For purposes practical, Miescher's
nevus never is present at birth. As a rule, it appears in the first
few years of life and in that sense is acquired. But the findings
histopathologic, in particular the extension of it routinely
throughout the reticular dermis and often with signs of neural
differentiation at the base of it, as is the situation here, are
those of a congenital nevus. Moreover, it differs strikingly
histopathologically from the common acquired melanocytic nevi,
namely, those named for Clark, Spitz, and Reed.
3) Even in the absence of an epidermis, a diagnosis
histopathologic of Miescher's nevus can be made without
equivocation. In most instances, no nests of melanocytes are found
in the epidermis of a Miescher's nevus and should they happen to be
there, they usually are stationed at the dermoepidermal
4) The degeneration of collagen seen as a band of homogenous
amphophilic material at the surface of this lesion is a consequence
of the lesion having been electrodesiccated lightly prior to its
having been biopsied by saucerization technique.
5) This patient also suffers from the residual effects of acne
conglobata, his face now being distorted by a rugose surface and by
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