Melanoma in Pregnancy: Case Report and Review of the Literature

Cancer in pregnancy is rare with an estimated incidence of 1 per 1000 pregnancies (1). The commonest malignancies are breast cancer, cervical cancer and malignant melanoma. Although the risk of transplacental transmission is low, development of cancer in the foetus has been described particularly in malignant melanoma (2).

We report a 33-year-old primigravida with stage 3 metastatic melanoma of the right axilla without evidence of distant spread, diagnosed at 24 weeks gestation following primary stage 2B melanoma 2 years earlier. Multidisciplinary planning between obstetrics, dermatology, neonatology, oncology, radiology and histopathology was initiated. Antenatal Ultrasound scans were normal. The baby was delivered by elective caesarean section at 35 weeks gestation. The placenta was examined microscopically and immunohistochemically with negative result. Clinical examination and postnatal imaging of the baby including MRI brain, ultrasound abdomen and chest X-ray were normal. A repeated abdominal ultrasound scan one month later was unremarkable.

Placental involvement has been described in 1.2% of mothers with malignant melanoma rising to 16.6% in patients with metastatic disease (3). The subsequent risk of transmission from affected placenta to foetus has been quoted at 22% (4). Without identifiable metastasis in the placenta, transmission to the foetus is very unlikely (3). There are no surveillance guidelines for the management of affected babies. Therefore an individualized, multidisciplinary approach is important. Circulating tumour DNA (ctDNA) will have an increasing role in the diagnosis and monitoring of melanoma (5). ctDNA in mother and baby perhaps will allow risk stratification and diagnosis in the future.