Metastatic Melanoma

Authors

Xiaoyan Zhou, MD (resident), David Frishberg, MD (attending)

Subject: Dermatopathology
Clinical History

The patient is a 25 year old male who presents with persistent left hip pain, inability to bear weight and loss of motion for half year. He also complained of loss of appetite and weight loss (25lb). On physical exam, he was cachectic. He had left hip pain with flexion and abduction and bony tenderness in lumbar back. Hip X-ray demonstrated an expansile, lytic lesion arising from the left greater trochanter with discontinuity of the overlying cortex and a soft tissue component. A CT-guided left femur biopsy is performed.

Further Immunohistochemical and Cytogenetic Workup

The tumor cells are positive for HMB45, Melan-A, and negative for Desmin and Actin. FISH for EWSR1 rearrangement is negative.

On further exploring of the history, the patient had a right ear melanocytic lesion 7 years ago. It was diagnosed as "atypical spitzoid melanocytic neoplasm" at outside hospital.

Diagnosis

Metastatic melanoma

Discussion

2% melanomas occur in patients who are less than 20 year old. However it is the most common malignant skin cancer in children and adolescents. Studies have shown that 1317 childhood and adolescent melanoma diagnosed between1973-2009. Among them, 93% occurred in whites and 60% in female.

The incidence of pediatric melanoma is increasing by an average of 2% per year for both boy and girl. It is suggested the increasing incidence are due to the prevalence of indoor tanning, increased capture of melanoma cases by cancer registries. For 10-20 year old group, the risk factors are the same as they are in adult population. For <10 year old group, risk factors include giant congenital melanocytic nevi, dysplastic nevus syndrome, xeroderma pigmentosum and immunodeficiency states.

The histologic features of childhood and adolescent melanoma are the same as adult melanoma generally. Patients under 10 years old tend to have thicker lesion and have higher positivity of lymph node biopsy. Interestingly, the mortality rate among adolescents and young adults (15–19 years) was roughly 8 to 18 times that seen in younger age groups.

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