Vulvar Basal Cell Carcinoma in Postmenopausal Women: Two Case Reports

Basal cell carcinoma (BCC) is major non-melanoma skin cancer, and its incidence is increasing worldwide [1]. The paramount environmental factor of BCC is sun exposure [2]. Risk factors related to the development of BCC include light skin color, tanning-bed use, ionizing radiation, and immunosuppression [2]. Although BCC has traditionally occurred in sun-exposed areas such as the head and neck, it may arise in sun-protected areas, including the breasts and genitalia [3, 4]. Herein, we present two cases of vulvar BCC in postmenopausal women.

BCC originates from the basal layer of the epidermis. Physical risk factors associated with BCC are fair skin, blond hair, and light eye color, which increase susceptibility to ultraviolet (UV) radiation damage [2]. Although the frequency of BCC correlates with lighter skin color, UV radiation is a pivotal predisposing factor, regardless of race [5]. The incidence of BCC in Asians has also increased globally [6].

Vulvar BCC is a rare clinical entity, accounting for less than 1% of all BCC and 2–4% of all vulvar cancers [4, 7]. Considering the main role of UV exposure in BCC, the mechanism underlying vulvar BCC development remains unknown. Trauma, chronic infection, and previous radiotherapy are considered risk factors for BCC in sun-protected areas, like sun-exposed areas [8]. Inappropriate activation of the sonic hedgehog (HH) signaling pathway plays an important role in the development of BCC [2]. Genetic mutations could help understand the mechanisms of BCC arising in sunprotected areas.

The appropriate diagnosis of vulvar BCC is challenging because of its rarity as well as asymptomatic or nonspecific clinical features such as vulvar lump, pruritus, pain, and bleeding [9]. It is an indolent tumor that rarely metastasizes and commonly occurs in the elderly [9]. Vulvar BCC is classified as a high-risk group for recurrence regardless of size [10]. Therefore, it is important to promptly perform a biopsy for histological confirmation when a suspicious skin lesion is found despite a previous benign lesion. It should be considered that vulvar dermatoses deteriorate the patient’s quality of life [11].

The mainstay of treatment for vulvar BCC is surgical excision. If Mohs micrographic surgery is feasible, it is the preferred method over wide local excision because it is possible to intraoperatively confirm margin involvement [12]. Although ambiguous margin safety due to clinical diversity remains in the high-risk group, wide local excision is adequate as primary therapy in most cases [10]. Systemic therapy is recommended in cases of positive margins after excision, locally advanced BCC, or metastatic BCC [10, 13]. One of the systemic therapies is vismodegib, a selective inhibitor of the HH signaling pathway [13]. Watson et al. reported a case of treatment with vismodegib in patients with pulmonary metastases of vulvar BCC [14].

The prognosis of BCC is related to the potential recurrent risk after primary therapy [15]. The recurrent risk depends on the lesion's location and histopathologic features [10, 15]. Poor prognostic features are associated with the following lists: (1) high-risk locations like the head, neck, hands, and anogenitalia, (2) aggressive histology such as morpheaform or infiltrate type, or (3) recurrent tumor [10, 15]. At least 30% of patients may develop recurrent BCC within 5 years [16]. Therefore, follow up including history and physical examination every 6 to 12 months up to 5 years, followed annually for the rest of the life is necessary [10].

Vulvar BCC is an uncommon malignant condition that is rare in the Asian population. As the symptoms are atypical, meticulous physical examination and prompt skin biopsy are important to avoid the delayed diagnosis, especially in the elderly. Although the disease has a favorable prognosis, regular follow-up over a long period is critical because of its locally aggressive nature and high risk of recurrence.