title: Melanoma of unknown primary site: presentation, treatment, and prognosis--a single institution study. University of Pennsylvania Pigmented Lesion Study Group.
abstract: BACKGROUND
  A retrospective analysis of 40 patients diagnosed with melanoma of unknown primary site (MUP) was undertaken to analyze the etiology and clinical behavior of this presentation.
  
  
  METHODS
  The patient records were located by a computer search of the Pigmented Lesion Clinic data base at the University of Pennsylvania. With the Cox proportional hazards model, the survival of the MUP patients with lymph node presentation was compared with that of patients with lymph node disease and a known concurrent primary melanoma.
  
  
  RESULTS
  Sixty-five percent of the patients presented with lymph node metastasis only, 28% presented with visceral lesions, and 8% presented with subcutaneous nodules. The prevalence of dysplastic nevi was 22.5%. The overall 4-year survival rate for the 40 MUP patients was 55% +/- 9%. The 4-year survival (57% +/- 12%) of patients with lymph node presentation was compared with that of patients presenting with lymph node disease and a known concurrent primary melanoma (19 +/- 6%). Survival was significantly different between the groups (P = 0.008). This survival difference remained significant (P = 0.02) even after adjustments for number of positive lymph nodes, year of diagnosis, and age at diagnosis.
  
  
  CONCLUSIONS
  This analysis revealed that MUP patients with lymph node metastasis survived significantly longer than patients diagnosed with lymph node metastasis concurrent with a known cutaneous primary melanoma. The prevalence of dysplastic nevi in the MUP patient series was intermediate between that reported among primary melanoma patients and that reported among population controls, suggesting the likelihood of a primary cutaneous origin for the metastatic melanoma.
authors.affiliation: University of Pennsylvania Medical Center, Philadelphia, USA.
authors.forename: K K
authors.initials: KK
authors.lastname: Anbari
authors.forename: L M
authors.initials: LM
authors.lastname: Schuchter
authors.forename: L P
authors.initials: LP
authors.lastname: Bucky
authors.forename: R
authors.initials: R
authors.lastname: Mick
authors.forename: M
authors.initials: M
authors.lastname: Synnestvedt
authors.forename: D
authors.initials: D
authors.lastname: Guerry
authors.forename: R
authors.initials: R
authors.lastname: Hamilton
authors.forename: A C
authors.initials: AC
authors.lastname: Halpern
mesh_terms: D000328:Adult; D000368:Aged; D004416:Dysplastic Nevus Syndrome / Q000473:pathology; D005192:Family Health; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008545:Melanoma / Q000209:etiology / Q000556:secondary* / Q000628:therapy*; D008875:Middle Aged; D009382:Neoplasms, Unknown Primary / Q000209:etiology / Q000473:pathology* / Q000628:therapy*; D011379:Prognosis; D012189:Retrospective Studies; D013472:Sunlight / Q000009:adverse effects; D016896:Treatment Outcome