INVASIVE, POLYPOID MELANOMA, WITH SURFACE ULCERATIONS, URETHRA
TUMOR THICKNESS, 2.5cm
AT LEAST CLARK’S LEVEL III
TUMOR EXTENDS TO BASE (MARGIN OF RESECTION)
Discussion:
This case is presented not for its diagnostic aspect but to focus on the aspect of determination of level of invasion in melanomas of mucous membranes, especially those with polypoid configuration.While the Clark and Breslow systems are easily applied to cutaneous melanomas, they are not easily applied to mucosal melanomas for prognostic evaluation. There are no analogous structures in the mucosal surfaces that correspond to the histologic layers of the skin, namely the granular layer, papillary and reticualr dermis.
Unlike in cutaneous melanomas, there is no universally accepted leveling scheme for mucosal melanomas. In 1975, Chung et al introduced a different leveling scheme for vulvar melanomas:
Level I- confined to epithelium
Level II- penetration into the dermis or lamina propria to a depth of 1mm or less
Level III- penetration between 1 and 2 mm deep into the subepithelial tissue
Level IV- invasion beyond 2mm into
fibrous and fibromuscular tissue but
not into the underlying fat
Level V- extension into underlying fat
According to Martin Mihm, M.D., in response to the query we placed with the American Joint Committee on Cancer:
“I basically don’t use this (referring to Chung’s method). I report the level as
Level II if microinvasion is less than 1mm.
If it is an expansile nodule up to 1mm or up to 2 mm, I call it a Level III, then IV if greater than
2 mm and V if greater than 3 mm and is widely invasive.”
“ The level of polypoidal malignant melanomas, invasive, without adjacent intra-epidermal component, is sometimes difficult to determine, if the tumor has not extended into the reticular dermis or the subcutaneous fat. For those polypoidal lesions that are not clearly identifiable as being present in the second or third level, the Group recommends that, because of their uniformly poor prognosis, all such polypoidal lesions be designated as invasive to the papillary-reticular interface.”
Cancer 32:1446-1457, 1973.
While the quoted article from the Cancer journal addresses polypoid melanomas and was also referred to by Mihm in his indirect communication with us when we sought help for determining the level of invasion in this case, the article does not clearly address how to determine the level of invasion in tumors where the“papillary-reticular interface” does not exist; hence our difficulty in reporting this case. A literature search failed to yield any article that specifically addresses how to report level of invasion in mucosal, polypoid melanomas.
Following said article, we reported the tumor as at least Clark Level III, being fully aware that it is not the best scheme to use for the kind of melanoma in question.
We also reported the thickness of the melanoma. The slide being distributed does not represent the maximum thickness of the tumor.
It would seem, based on the few published articles in the literature on urethral melanomas that conventional prognostic factors such as depth of
invasion and tumor stage do not appear to play as important a role in predicting survival as the location in the mucosal membrane and the nodular growth pattern that is almost always present in these tumors.
We have explained our difficulty in reporting the level of invasion to the clinician and considered sending out the case.The urologist commented that it won’t be necessary since he intends to refer the patient to a tertiary facility for further management.
Submitted by Melinda Labuguen, M.D. from St. Mary's Hospital, Apple Valley, California.
References:
Chung A et al: Malignant Melanoma of the Vulva: A Report of 44 Cases. Obstetrics and Gynecology 45(6):638-646, June 1975
Mc Govern V et al: The Classification of Malignant Melanoma and its Histologic Reporting.Cancer 32:1446-1457, 1973
Oliva E et al. Primary Malignant Melanoma of the Urethra: A Clinicopathologic Analysis of 15 Cases. American Journal of Surgical Pathology 24(6):785-796, June 2000
Thoelke A et al. Primary Extracutaneous Melanoma: A Comprehensive Review with Emphasis on Treatment. Onkologie.27:492-499, 2004
Mihm, Martin in a personal communication through the American Joint Committee on Cancer
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