Sentinel Lymph Node Biopsy in Histologically Ambiguous Melanocytic Tumors With Spitzoid Features (So-Called Atypical Spitzoid Tumors)

Abstract

SLN biopsy offers a means of assessing the metastatic potential of atypical spitzoid tumors and aids in the management of these patients by selecting patients who may benefit from a regional node field dissection and those in whom the use of adjuvant therapies could be considered.

Sentinel lymph node metastasis is not predictive of poor outcome in patients with problematic spitzoid melanocytic tumors

“…In our cohort, 35% of the patients with SM had SLN metastases. Both this figure and our 26% involvement by AST are consistent with prior reports that show a wide range from 17% to 71% SLN involvement by AST or SM [2,11,[14][15][16][17][18][19][20][21]25,30,31]. Regardless of the series cited, these figures all exceed the 16% SLN positivity associated with bona fide primary cutaneous melanomas [32].…”

“…Some observers recommend using the term atypical Spitz tumor for all Spitz nevi with any atypical histologic feature and simply "melanoma" for melanomas with spitzoid features [27], thus using the term AST and including all SM in the category of melanoma. Consensus meetings have led to the identification of some unifying concepts [16,25]: (1) histologically conventional benign Spitz nevi are not associated with metastasis [27,28], (2) atypical spindled and epithelioid melanocytic proliferations resembling Spitz nevi but with cytologic and/or architectural atypia (eg, AST) may frequently be associated with SLN metastases [2,6,[10][11][12][13][14][15][16][17][18][19][20][21], and (3) SM represents atypical spindled and epithelioid melanocytic tumors that share many cytologic and architectural features with melanoma; they are considered to be melanoma by most observers, possibly with a better prognosis than conventional melanoma [29,30]. AST and SM may exist on a continuum with Spitz nevi on one end and SM on the other [16,27].…”

“…Many of these patients who were identified to have positive SLN were treated with completion lymphadenectomy (CLND) and adjuvant therapy, often interferon α. Over the past decade, several reports suggest that SLN status in patients with AST and SM may not have the same prognostic predictive value as in patients with conventional melanoma [2,6,[10][11][12][13][14][15][16][17][18][19][20][21]. Patients with AST or SM and positive SLN appeared to have better long-term outcomes than those with conventional melanomas of equivalent stage [6,13,15,16,19].…”

Difficulties in the diagnosis of spitzoid melanocytic lesions

“…In the past, the presence of any atypical cells in SLNs in this setting was taken as evidence of aggressive behavior and the primary skin lesions were retrospectively classified as melanoma. However, as multiple series demonstrate, the vast majority of these lesions do not show a similar aggressive behavior to conventional melanoma [9, [14][15][16]. The pattern of lymph node involvement, tumor burden and presence of mitotic activity are important features to identify when evaluating melanocytic deposits in this setting.…”

La tumeur de Spitz et le mélanocytome épithélioïde pigmenté : de nouveaux cadres nosologiques pour des tumeurs souvent mal définies

“…Il est d'ailleurs probable que certains patients étiquetés « TS avec métastases » rentrent dans ce groupe de « micrométastases » du GS. Par ailleurs, lorsqu'on reprend les cinq grandes séries récemment publiées concernant des patients ayant eu une étude du GS après un diagnostic de TSA [27,29,[31][32][33], on se rend compte qu'aucun des patients considérés comme ayant un mélanome métastatique n'est décédé de son mélanome avec un suivi toutefois limité (en moyenne de 23 mois). S'il s'agit réellement de mélanomes, l'évolution naturelle de ces tumeurs avec « métastase ganglionnaire » est significativement meilleure que celle du mélanome conventionnel.…”