Malignant Melanoma : Wheeless' Textbook of Orthopaedics

- See: Tumors of Soft Tissue

- Prognosis:
- prognosis of malignant melanoma worsens w/ increasing tumor thickness and also appears to be related to tumor site, age, and sex;
- lesions on the scalp, hands, and feet, particularly in older pts and males, all have a poorer prognosis;
- tumor thickness & 5 year survival rate:
- tumor thickness < 0.75 mm have > 95% survival rate;
- tumor thickness > 4 mm have < 50% surviva ratel;
- w/ nodal metastasis five-year survival rate declines to 36%;
- w/ metastases survival is < 5%;
- lymph nodes and lymphatic mapping:
- useful for identifying metastasis to the sentinel lymph node;
- observation that the classic lymph node dissection would not necessarily identify metastasis to the SLN (which was the case in 10/12 patients in the study by Joseph, et al (1999)
           - in contrast, patients w/ a negative SLN can be spared the morbidity of a complete lymph node dissection;
- references:
   - Lymphatic mapping for melanomas of the upper extremity.
                   - Sentinel-Node Biopsy or Nodal Observation in Melanoma.
   - Prognostic factors in patients with melanoma metastatic to axillary or inguinal lymph nodes. A multivariate analysis.

- Junctional Nevi:
- pigmented tumors w/ benign melanocytes in epidermis & arranged in nests;
- acquired variety are smaller than 6 mm;
- benign pigmented tumors usually do not produce discomfort or other functional deficit;

- Subungual Melanoma:
- first described in 1886 by Jonathan Hutchinson who noted that though it looked like septic whitlow, lesion was malignant from beginning;
- he noted thatt not all were pigmented but that at edges there was always slight black discoloration and this, however, slight, confirmed the diagnosis;
- growth usually appears in the form of a black fungating ulcer involving the nail sulcus and matrix and elevating the nail;
- black border along the edge of the nail is pathognomonic;
- may appear as pigmented band originating from nail matrix;
- in blacks and in some orientals pigmented bands may be normal, but pathology should be suspected in caucasions;
- onset of pigmented band after the age of 40 is suspicious;
- also remember that in blacks upto 25% of melanomas occur as subungual lesions;
- in the report by O'Leary JA, et al (2000), 93 patients w/ diagnoses of subungual melanoma were followed w/ a median duration of followup of 5.2 years;
- 83 % of patients presented with Stage I disease, whereas 17% had nodal or distant disease;
- 53 % had locally advanced disease at presentation;
- operative therapy consisted of amputation;
- elective lymph node dissection was performed in 34 patients (37%) for Stage I tumors of intermediate thickness;
- therapeutic node dissection was required in 16 patients (17%) for positive nodes
- 5-year survival was 74% for patients with Stage I disease and 40% for patients with Stage II disease;
- diff dx: (of nail hyperpigmentataion);
- hematoma
- chlorpromazine
- antimalarial meds
- heavy metal toxicity
- Peutz-Jeghers Syndrome
- treatment:
- controversial;
- when subungual melanoma involves the index nail, consider ray amputation since the index ray is functionally less important than the other rays;
- references:
- NEJM Image Challenge - Subungual melanoma.
- Surgical aspects of subungual malignant melanomas. The Scottish Melanoma Group.
- Subungual melanoma. A review of 93 cases with identification of prognostic variables.