Cancerous growth of melanocytes results in melanoma. The vast majority of melanomas are from the skin but malignant melanomas have been described in nearly every organ of the body.

Malignant melanoma of skin

See separate article Malignant Melanoma of Skin.

Choroidal melanoma

See separate article Choroidal Melanoma.

Melanoma of the central nervous system¹

• The most common form of melanoma in the central nervous system (CNS) is metastases of cutaneous melanoma. It is rare as a primary malignancy of the CNS and accounts for about 1% of melanomas.
• Primary intracranial melanoma can arise from the leptomeninges or dura mater.
• Primary melanomas of the pineal region (see separate article Pineal Tumours) are very rare and may be difficult to diagnose.^2,3
• Spread to the meninges gives a worse prognosis.⁴
• Neurocutaneous melanoma is a congenital disorder in infants with giant hairy melanocytic naevi. The leptomeningeal tissues are invaded, involving the brain or spinal cord. Severe neurological compromise or death results.
• Melanomas that metastasise to the CNS are incurable. Treatment is aimed at reducing the size of the tumour by surgery and/or palliative radiotherapy and supportive palliative care. The use of steroids provides symptom relief by decreasing cerebral oedema.

Mucosal melanoma⁵

Mucosal melanoma may particularly present in the anorectum, nasal cavity, genitourinary tract, upper gastrointestinal tract and maxillary sinus.⁶

Head and neck

See separate article Cancers of the Head and Neck.

• Primary mucosal melanoma of the head and neck is rare and is associated with a poor outcome.
• Standard therapy is surgical resection, possibly associated with adjuvant radiation and chemotherapy.⁷
• Melanoma of oral mucosa is very uncommon and accounts for less than 1% of all melanomas.⁸ Approximately one third of patients have lymph node involvement at presentation.⁹ The outlook is poor with a 5-year survival of 10-25% and a median survival of less than 2 years.
• Sinonasal melanomas have a similar prognosis to oral melanomas.¹⁰

Gastrointestinal melanomas

• Most gastrointestinal melanomas are metastatic in origin but primary malignant melanomas of the gastrointestinal tract do occur. Malignant melanoma is one of the most common malignancies to metastasise to the gastrointestinal tract. Metastases to the gastrointestinal tract can present at the time of primary diagnosis or decades later as the first sign of recurrence. Symptoms may include abdominal pain, dysphagia, small bowel obstruction, haematemesis, and melaena.¹¹
• Small intestine melanomas can be primary tumours or metastases from cutaneous, ocular or anal melanomas. Primary intestinal melanoma is extremely rare, whereas metastatic melanoma of the small bowel is common because of the tendency for cutaneous melanoma to metastasise to the gastrointestinal tract. Patients with primary melanoma of the small intestine have a worse prognosis than do patients with metastases of cutaneous melanoma.¹²
• Anorectal melanoma (see also separate article Anal Carcinoma) is uncommon with a median survival of less than 20 months. Abdominoperineal resection has historically been the treatment of choice but there has been a shift toward less-mutilating wide local excisions.¹³

Genitourinary melanomas

• Genitourinary melanoma is rare and classically associated with a poor prognosis.¹⁴
• Partial penectomy or wide local excision provides effective local control for low-stage penile or urethral melanomas and all scrotal lesions. Prophylactic modified inguinal lymphadenectomy should be considered in patients with penile, scrotal and anterior urethral melanoma.¹⁴
• Primary melanoma of the female genital system is extremely rare.¹⁵ Surgery remains the initial treatment of choice for localised melanomas of the female genital tract, with less radical, organ function-preserving resections. Radiotherapy may play a role in the treatment of patients with close resection margins, regional nodal metastasis or unresectable tumours. The results of treatment for female genital tract melanomas are poor.¹⁶
• Melanoma involving the ovary is rare and predominantly seen in women of reproductive age. The tumour is most often metastatic from another site and is unilateral in most cases. Melanoma of the ovary is associated with a poor prognosis.¹⁷

Melanoma of unknown primary site

See also separate article Malignancy of Unknown Origin.

• No primary lesion is identified in 10-20% of patients presenting with palpable evidence of regional metastatic melanoma. Metastatic melanoma with an unknown primary site may be found in lymph nodes only.¹⁸
• Patients with occult primary melanoma may present with a solitary metastasis, lymph node disease or systemic disease.¹⁹
• All patients should have a thorough examination of the skin.¹⁹
• Occult primary uveal tract melanoma nearly always causes liver metastases before these are apparent at other sites.¹⁹
• For patients presenting with inguinal lymphadenopathy, examination of the genital and urinary tracts and anorectum is especially relevant.¹⁹
• All patients should be staged with CT scans of the head, chest, abdomen and pelvis.¹⁹
• Some studies have found a significantly better postoperative survival for melanoma of unknown primary (MUP) versus melanoma of known primary (MKP), suggesting a strong endogenous immune response against the primary melanoma.^20,21 However, other studies have shown similar 5-year survival rates for MUP and MKP.²²

Document references

1. Schaffert A; CNS Melanoma, Medscape, Jan 2010
2. Martin-Blondel G, Rousseau A, Boch AL, et al; Primary pineal melanoma with leptomeningeal spreading: case report and review of Clin Neuropathol. 2009 Sep-Oct;28(5):387-94. [abstract]
3. Bookland M, Anderson WS, Biser-Rohrbaugh A, et al; Primary pineal malignant melanoma. Pediatr Neurosurg. 2007;43(4):303-8. [abstract]
4. Greco Crasto S, Soffietti R, Bradac GB, et al; Primitive cerebral melanoma: case report and review of the literature. Surg Neurol. 2001 Mar;55(3):163-8; discussion 168. [abstract]
5. Collins B et al; Oral Malignant Melanoma, Medscape, May 2011
6. Kim HS, Kim EK, Jun HJ, et al; Noncutaneous malignant melanoma: a prognostic model from a retrospective BMC Cancer. 2010 Apr 28;10:167. [abstract]
7. Mendenhall WM, Amdur RJ, Hinerman RW, et al; Head and neck mucosal melanoma. Am J Clin Oncol. 2005 Dec;28(6):626-30. [abstract]
8. Hicks MJ, Flaitz CM; Oral mucosal melanoma: epidemiology and pathobiology. Oral Oncol. 2000 Mar;36(2):152-69. [abstract]
9. Patrick RJ, Fenske NA, Messina JL; Primary mucosal melanoma. J Am Acad Dermatol. 2007 May;56(5):828-34. Epub 2007 Mar 8. [abstract]
10. Prasad ML, Busam KJ, Patel SG, et al; Clinicopathologic differences in malignant melanoma arising in oral squamous and Arch Pathol Lab Med. 2003 Aug;127(8):997-1002. [abstract]
11. Liang KV, Sanderson SO, Nowakowski GS, et al; Metastatic malignant melanoma of the gastrointestinal tract. Mayo Clin Proc. 2006 Apr;81(4):511-6. [abstract]
12. Lens M, Bataille V, Krivokapic Z; Melanoma of the small intestine. Lancet Oncol. 2009 May;10(5):516-21. [abstract]
13. Meguerditchian AN, Meterissian SH, Dunn KB; Anorectal melanoma: diagnosis and treatment. Dis Colon Rectum. 2011 May;54(5):638-44. [abstract]
14. Sanchez-Ortiz R, Huang SF, Tamboli P, et al; Melanoma of the penis, scrotum and male urethra: a 40-year single institution J Urol. 2005 Jun;173(6):1958-65. [abstract]
15. Jahnke A, Makovitzky J, Briese V; Primary melanoma of the female genital system: a report of 10 cases and review of Anticancer Res. 2005 May-Jun;25(3A):1567-74. [abstract]
16. Sugiyama VE, Chan JK, Kapp DS; Management of melanomas of the female genital tract. Curr Opin Oncol. 2008 Sep;20(5):565-9. [abstract]
17. Gupta D, Deavers MT, Silva EG, et al; Malignant melanoma involving the ovary: a clinicopathologic and Am J Surg Pathol. 2004 Jun;28(6):771-80. [abstract]
18. Tan WW; Malignant Melanoma, Medscape, Apr 2011
19. Revised U.K. guidelines for the management of cutaneous melanoma 2010, British Association of Dermatologists
20. Lee CC, Faries MB, Wanek LA, et al; Improved survival after lymphadenectomy for nodal metastasis from an unknown J Clin Oncol. 2008 Feb 1;26(4):535-41. [abstract]
21. Lee CC, Faries MB, Wanek LA, et al; Improved survival for stage IV melanoma from an unknown primary site. J Clin Oncol. 2009 Jul 20;27(21):3489-95. Epub 2009 May 18. [abstract]
22. Katz KA, Jonasch E, Hodi FS, et al; Melanoma of unknown primary: experience at Massachusetts General Hospital and Melanoma Res. 2005 Feb;15(1):77-82. [abstract]

Acknowledgements