ARTICLE
Auteur(s) :, Roberto
Betti*, Silvano Menni, Carlo Crosti
University of Milan – Clinica Dermatologica, Ospedale San Paolo,
Via di Rudinì 8, 20142 Milano Italy
accepté le 3 Août 2004
Melanoma of the penis is rare and accounts for less than 0.2% of
all melanomas in men [1, 2].Of these about 50% are located on the
mucosa of the glans [3]. All authors stress the importance of an
early diagnosis because the prognosis is very poor [4].The use of
dermoscopy has proved to be useful for improving the diagnostic
accuracy of pigmented skin lesions [5]. For this reason, the
systematic use of dermoscopy is desirable to facilitate the
diagnosis and the preoperative assessment of cutaneous and mucosal
pigmented lesions.We report a case of an in situ melanoma of the
glans penis, in which dermoscopy suggested the correct diagnosis at
the beginning of the diagnostic work-up.To our knowledge this is
the third report of an in situ melanoma of the penis [4, 6] and the
first dermoscopy analysis of a mucosal melanoma.
Case report
An otherwise healthy 64-year-old Caucasian man presented with an
asymptomatic brownish pigmented macula on his glans penis. The
lesion had appeared about 18 months before.
Physical examination revealed a solitary, uniform, smooth, dark
brown, pigmented macula measuring 8 × 7 mm, on the ventral surface
of the glans, in a paramedian location near the fraenum ( (figure 1) ).
The lesion had distinct borders and was asymmetrical in shape.
It had slowly enlarged during the last year. Inguinal lymph nodes
were not palpable.
Dermoscopy revealed a prominent, wide and irregular pigment
network, particularly at the center of the lesion. The pigment
network stopped abruptly at the periphery.
A fine, more peripheral pigment network was observed in
particular near the medial portion of the lesion ( (figure 2) ).
We performed a diagnostic biopsy.
On histopathological examination, the hematoxylin-eosin stained
sections showed numerous atypical melanocytic cells with large,
hyperchromatic nuclei and abundant cytoplasm, often arranged in
nests and in a lentiginous pattern along the basal layer. Atypical
melanocytic cells were also scattered throughout the upper layers
of the epidermis. No dermal invasion by atypical melanocytes was
seen ( (figure
3) ). The melanoma cells showed positive staining with the
monoclonal antibody HMB45 (monoclonal mouse antihuman melanoma
HMB45, DAKO; Ca.) (data not shown), which provided further evidence
of the epidermal localization of the tumor. The diagnosis of
melanoma in situ was made.
All the haematologic, radiologic and sonographic (regional
lymph-nodes and liver) investigations were negative.
The patient was referred to the urology department for surgical
excision, i.e. partial resection of the glans penis.
The patient is in good health without recurrence or metastases 2
years after the surgical operation.
Clinical and sonographic follow-up examinations were
negative.
Discussion
Melanoma of the penis (MP) is rare. Most of the reported
dermatologic cases are described in Japanese literature [7]. They
occurred in sixth and seventh decade of life and were located on
glans penis (55%), prepuce (28%), penile shaft (9%) and the
urethral meatus (8%) [8]. At presentation, about 50% of patients
with MP showed local or distant metastases [8]. Early diagnosis is
very important, because the risk of distant metastases is high [2].
For this reason initial surgical therapy must be aggressive. In
most reported cases of MP, partial (MP of prepuce) or total (MP of
the glans) amputation of the penis was performed [2].
In a previous report of melanoma in situ of the penis shaft a
0.5 cm margin excision was performed [4]. Even considering the age
of our patient and the mucosal site, we preferred subtotal
amputation of the glans.
The prognostic importance of early diagnosis induced us to
consider dermoscopy as a particularly useful tool for the
evaluation of mucosal pigmented lesions, as their clinical features
resemble those of melanoma [9].
The maculae of lentigo are small, sharply demarcated, uniform
and light brown. Dermoscopy shows a delicate, regularly sized,
pigment network throughout the lesion [10, 11]. The histologic
counterpart might be the elongated honeycomb-like rete ridge.
Melanoses are characterized by single or numerous irregularly
outlined maculae that sometimes have a variegated brownish
pigmentation. Dermoscopy shows a diffuse so-called “structureless”
pigmentation, sometimes with a peculiar, partially linear,
partially curvilinear, parallel pattern of brown streaks [10-12].
The histologic counterpart might be basal hyperpigmentation and
dermal melanophages.
In melanosis and lentigines typical dermoscopic features of
melanoma i.e. atypical pigment network, irregular black dots and
globules, or whitish-blue veil, are not seen.
To our knowledge, the dermoscopic features of melanoma in situ
have not been described in the literature, but “there is no reason
to expect an ELM pattern of mucosal melanoma different from that of
melanoma of the skin, the changes being histologically identical”
[12].
We observed an irregular, broad and prominent network ending
abruptly at the periphery, so we thought that these findings might
be suggestive of mucosal melanoma in situ.
We cannot be certain that the atypical pigment network described
is a specific feature of a mucosal in situ melanoma, but this is
probable in view of the observations in in situ cutaneous melanoma.
Further studies on the ELM features of mucosal malignant pigmented
lesions will provide useful information for the preoperative
assessment of these lesions.
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