Melanoma in Pregnancy
Although approximately 1/3 of the increasing numbers of women who are diagnosed with melanoma each year are of childbearing age, melanoma accounts for about 8% of malignancies diagnosed during pregnancy. The overall incidence of melanoma in pregnancy is estimated to be 0.14 to 2.8 cases per 1000 births. While occurring extremely rarely, melanoma is one of the most common tumors known to metastasize to the placenta and fetus.
Despite the fact that melanocytic nevi (moles) commonly become larger and darker under the hormonal influence of pregnancy, due to increased levels of estrogen and melanocyte stimulating hormone, there exists no conclusive evidence that pregnancy significantly affects the biologic aggressiveness of a melanoma in terms of increasing the incidence of metastasis or lowering overall survival. Moreover, pregnancy occurring either before or after the diagnosis and treatment of melanoma similarly appears to have no significant effect on the clinical course of the disease. Based on the data presently available, the termination of pregnancy of a patient recently diagnosed with melanoma as a therapeutic measure cannot be recommended. However, because the overwhelming (>75%) majority of melanoma recurrences occur within 2–3 years after treatment of the primary lesion, many women are encouraged to avoid becoming pregnant for that period of time postoperatively.
The frequent observation that melanocytic lesions may become more pronounced during pregnancy makes the diagnosis of melanoma even more difficult. However, as in any other patient, any cutaneous lesion suspicious for melanoma in a pregnant patient should be biopsied without delay. This is accomplished with shave, punch, incisional, or preferably complete excisional biopsy, which may be performed safely in the pregnant patient under local lidocaine anesthesia, without the addition of epinephrine. While the majority of these biopsy procedures may be carried out safely and rapidly in the office setting, the excision of larger lesions may be more prudently performed in the ambulatory surgery unit with an anesthesiologist knowledgeable in the care of the pregnant patient in attendance, with intraoperative fetal monitoring during the later stages of pregnancy if appropriate.
Once the diagnosis of melanoma is confirmed histologically, an abbreviated metastatic survey may be ordered, but surgical treatment is planned commensurate with the thickness of the primary lesion and clinical stage of disease. Routine laboratory tests including determination of LDH level should be ordered. Radiologic workup may include X rays of the chest, which can be performed safely during pregnancy with the appropriate shielding. In patients with melanomas >0.8 mm or those with palpable regional nodal metastases, sonographic examination of the abdomen and liver may be performed to search for visceral (internal organ) metastases instead of CT scanning with intravenous contrast, which is not recommended during the early stages of pregnancy.
Wide local excision with 5 mm margins is performed under local anesthesia, in the ambulatory surgery suite, in patients with melanoma in situ. Invasive melanomas less than 1.0mm thick are similarly treated under local anesthesia with wide and deep excision, maintaining 1 cm margins. Both of these procedures are performed with appropriate maternal fetal monitoring.
Patients with melanomas >1.0 mm undergo a wide and deep excision, maintaining 2 cm margins. The surgery is done under general anesthesia, administered by an anesthesiologist with experience in the care of the obstetrical patient. Formal therapeutic regional lymph node dissection is performed at the same time when there are palpable nodal metastases. The treatment of the regional nodes in patients with melanomas >0.8 mm and with no clinical evidence of metastatic disease is less clear. Although intraoperative lymphatic mapping using vital blue dye and radio labeled technetium sulfur colloid and sentinel lymphadenectomy is currently the accepted approach to non-pregnant patients with melanomas >0.8 mm and no clinical evidence of nodal metastases, the accuracy and safety of this procedure in pregnant patients has not yet been studied completely and confirmed. Therefore the surgical approach to the regional lymph nodes in this group of patients must be individualized, with all possibilities discussed in detail with the patient and her family. As no significant survival advantage has been demonstrated in prospective randomized clinical trials for patients with melanomas undergoing elective regional lymph node dissection, a reasonable approach could be wide and deep excision of the primary melanoma and no treatment of the regional nodes at that time. Regional lymph node dissection may be performed at a later date should palpable nodal metastases become evident or after the completion of pregnancy.