Low power photomicrograph of an atypical Spitzoid melanocytic tumor.
Issues in Dermatopathology
The sentinel lymph node biopsy (SLN) has emerged as an important first step in the therapeutic regimen for cutaneous melanomas. Recently, a series of articles have examined the utility of performing a SLN biopsy for diagnostically controversial and borderline melanocytic neoplasms. These tumors have variously been termed minimal deviation melanoma, Spitz nevus-type, borderline nevomelanocytic neoplasm, nevoid melanoma, and atypical Spitz nevus/tumor atypical Spitz nevi, and diagnostically controversial Spitzoid melanocytic tumors. All of these tumors shared histopathologic traits of both melanoma and Spitz nevi and, depending upon the site of the study, included histopathologic parameters such as: increased deep dermal mitotic figures, nuclear pleomorphism with focal epithelioid cell atypia, incomplete maturation, and focal sheet-like growth. In all cases, experienced board certified dermatopathologists reviewed the cases.
The table below summarizes the results of four centers that performed a SLN biopsy for these tumors. A positive SLN biopsy was present in 30 to 50% of cases.
Obviously, the sample sizes are small and biased toward a very select group of diagnostically challenging melanocytic neoplasms. Nonetheless these distressing studies should serve notice to both treating physicians and dermatopathologists alike that current histopathologic diagnostic criteria to distinguish melanomas from atypical Spitz nevi are clearly not as precise as we would intend them to be. At least in these selected cases, a SLN biopsy may be justified.
Sentinel lymph node biopsy in patients with "atypical Spitz tumors." A report on 12 cases. Hum Pathol. 2006 Jul;37(7):816-23. Urso C, etal.
Sentinel lymph node biopsy for atypical melanocytic lesions with spitzoid features. Ann Surg Oncol. 2006 Dec;13(12):1664-70. Gamblin TC, etal.
Submitted by Paul K. Shitabata, M.D.
This is a bunch of junk. When I was a fellow I saw a 15 year old kid who had bilateral neck dissections for a sentinel node positive "atypical spitz nevus" The kid had all kinds of problems resulting from his surgery when the whole thing was probably unnecessary. The problem here is that nobody knows how commonly garden variety Spitz nevi cells traffic in and out of lymph nodes since we don't normally check the lymph nodes status in these patients. Now you have people taking a debatable diagnostic test SLNB from adults with melanoma and using it on children (since they compromise the bulk of Spitz nevi patients) with arguably benign lesions and for what purpose? This is underscored by the fact that a recent review article that showed that nearly 40% of pediatric patients with either melanoma or Spitz nevi were found to have SLNB positive nodes yet none of the patients developed any recurrences. In contrast, adults had a positive SLNB in 18% of cases and 25% of these went on to recur. If there is a 40% chance of a + SLNB why do it? Moreover if having a + SLNB doesn't appear to correlate with prognosis then what's the point of the procedure???? Just my thoughts.
The sentinel lymph node for melanoma is an interesting controversy. For borderline lesions even more controversial. I am suspicious of the studies previously done. Sampling the node is an issue. Interpretation is another issue and varies between pathologists and benefit to the patient isn't clear. I need to sit down and read these studies in detail to analyze their pitfalls.
First Posted on September 21, 2007
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