Stains
HMB45

Author: Nat Pernick, M.D. (see Authors page)

Revised: 1 December 2015, last major update October 2012

Copyright: (c) 2002-2015, PathologyOutlines.com, Inc.

PubMed Search: HMB45 [title]

Cite this page: HMB45. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/stainshmb45.html. Accessed December 3rd, 2016.
Definition / General
  • Human Melanoma Black, discovered in 1986 (Am J Pathol 1986;123:195)
  • Monoclonal antibody originally identified from melanoma abstract, recognizes melanosomal glycoprotein gp100 (Pmel17)
  • Membrane protein required to form melanosomal fibrils, facilitates maturation of stage I pre-melanosomes to stage II
  • Identifies oncofetal glycoconjugate associated with immature melanosomes and probably related to the tyrosinase enzymatic system (J Histochem Cytochem 1992;40:207)
Uses by Pathologists
  • Common marker to confirm melanoma (invasive melanomas with paradoxical maturation show at least focal deep HMB45 reactivity, in contrast to nevi, which are negative in deep dermis)
  • Evaluating sentinel lymph nodes for melanoma (Am J Surg Pathol 2001;25:1039)
  • Diagnosis (or ruling out diagnosis) of perivascular epithelioid cell tumors (angiomyolipoma, lymphangioleiomyomatoisis, PEComa, clear cell "sugar" tumor)
Micro Images

Images hosted on PathOut server:

Missing Image

Bladder, paraganglioma

Missing Image

Kidney, angiomyolipoma

Missing Image

Kidney, atypical epithelioid angiomyolipoma

Missing Image

Uterus, melanoma



Images hosted on Other servers:

Missing Image

Esophagus, melanoma

Missing Image Missing Image

Kidney, angiomyolipoma

Missing Image

Kidney, atypical epithelioid angiomyolipoma

Missing Image

Lung, clear cell "sugar" tumor

Missing Image

Lung, lymphangioleiomyomatosis

Missing Image Missing Image

Perivascular epithelioid cell tumors

Missing Image

Skin, melanoma

Missing Image Missing Image

Skin, nevi and melanomas

Cytology Images

Image hosted on Other server:

Missing Image

Thyroid, metastatic melanoma

Positive Staining - Normal
  • Lymph nodes: scattered mononuclear cells
  • Skin: junctional melanocytes, activated melanocytes
Positive Staining - Disease
  • Skin and other sites: melanoma (85-90%, see exceptions under Negative staining)
    • Also blue nevus, Spitz nevus (Spitz nevi may be HMB45- at other sites)
    • Nevus cells may be HMB45+ in intraepidermal and superficial dermal component
    • Nevus cells may also have weak nuclear staining that is overwhelmed by hematoxylin and usually not seen (Mod Pathol 2008;21:1121)
  • Angiomyolipoma (various sites, usually negative in nasal cavity)
  • Clear cell sarcoma of soft tissue (Am J Surg Pathol 2008;32:452)
  • Clear cell "sugar" tumor (Am J Surg Pathol 2002;26:670)
  • Epithelioid sarcoma (occasional)
  • Kidney: t(6;11)(p21;q12) renal cell carcinoma (Hum Pathol 2012;43:726)
  • Lymphangioleiomyomatosis (also stains nonproliferative cells)
  • Melanocytosis
  • PEComa (Am J Surg Pathol 2005;29:1558)
  • Pheochromocytoma (30%, Arch Pathol Lab Med 1992;116:151)
  • Pigmented neural tumors (some), including some nerve sheath tumors, some neurofibromas (Hum Pathol 2005;36:871), pigmented neuroectodermal tumor of infancy
  • Tuberous sclerosis complex components
Negative Staining
  • Adult / resting melanocytes
  • Some melanomas: desmoplastic, oral mucosal, spindle cell (but 50% of HMB45 negative melanoma cells have premelanosomes on EM)
  • Atypical fibroxanthoma
  • Epithelioid malignant peripheral nerve sheath tumors
  • Leiomyosarcoma, liposarcoma
  • Paget disease of breast, scrotum, vulva
  • Pigmented dermatofibrosarcoma protuberans, pigmented epithelioid melanocytoma
  • Uterine tumors resembling ovarian sex cord tumors (Am J Surg Pathol 2010;34:1749)