(20) These changes, which have been referred to as pseudomelanoma, (19) may be purely junctional (mimicking melanoma in situ) or extend to the superficial dermal component (mimicking invasive melanoma) (Figure 1, A and B).
Pseudomelanoma: recurrent melanocytic nevus following partial surgical removal.
Pseudomelanomas following Stevens-Johnson syndrome.
The first is that the nevus will recur in the scar years later and be indistinguishable from melanoma--the so-called pseudomelanoma phenomenon.
It could also be the case of pseudomelanoma phenomenon where it's a nevus to start with but it comes back looking more atypical, so it's incorrectly diagnosed as melanoma.
Pseudomelanoma due to hypermature cataract can be identified using USG by the presence of an echodense cortex forming anterior and posterior borders, lack of contiguity with the uvea, and ring melanomalike visibility in all four quadrants.
Ciliary body and choroidal pseudomelanoma from ultrasonographic imaging of hypermature cataract in 20 cases.
In 1975, Kornberg and Ackerman (6) reported that pigmented RN could closely resemble superficial spreading malignant melanoma (SSMM), both clinically and histologically, and proposed the term pseudomelanoma to describe this benign phenomenon.
Of these features, (3), (4), (5), and (6) were held in common with SSMM, whereas (1), (2), (7), and dermal fibrosis were found to distinguish pseudomelanoma. Furthermore, the fibrosis found in "pseudomelanoma" was a result of the trauma of the previous biopsy, in contrast to the fibrosis found in SSMM, which was associated with a relative paucity of melanocytes and melanin in the overlying epidermis, and which signified regression.
In 1986, Trau et al (7) reported a case of pseudomelanoma after C[O.sub.2] laser ablation therapy for a congenital nevus.
Park et al (3) concluded that RN with atypical features rarely resembled SSMM, thereby posing "significant diagnostic difficulties," but added that most RN did not mimic melanoma histologically; therefore, they did not recommend the term pseudomelanoma. (3) Recently, it has been observed that some cases of RN have histopathologic overlap with regression in melanoma.