Primary vulvar cancer is a rare tumor accounting for approximately 4% of all gynecologic malignancies.
Squamous cell carcinoma (SCC), the most usual type (>85% of all vulvar cancers), has traditionally been regarded as a disease of postmenopausal women, although the mean age of incidence has fallen in recent years owing to the increase in human papilloma virus (HPV) infections worldwide.
There are two type of SCC based on association with HPV.
HPV-positive cancers mainly arise in women younger than 60 years and are correlated with vulvar intraepithelial neoplasia, have a tendency to be multifocal and multicentric, and may be combined with analogous lesions of the cervix and vagina.
HPV-negative cancers mostly arise in old women (>60 years) and are correlated with vulvar inflammation and lichen sclerosus.
Vulvar cancer generally extends slowly and tends to be locally infiltrative prior to invading the local lymph nodes in the groin.
Regional extension may involve the vagina, urethra, and anus, but rarely the bladder and bone.
In more advanced cases, the pelvic nodes can be involved.
The lymphatic drainage from the vulva is primarily via the superficial inguinal nodes.
Lateral vulvar carcinomas drain to the ipsilateral inguinal nodes but midline lesions (or within 1cm of the midline) can drain bilaterally.
Metastatic diffusion outside the pelvis is unusual in vulvar cancer.
Initial diagnosis is made by gynaecological examination and incision biopsy.
The most important prognostic factors include size of the primary tumor and the regional lymph node status.
The final diagnosis is established by histological examination of the primary tumour and lymph node specimens.
The treatment of vulvar cancer should be personalized, including tailored primary tumor resection and lymph nodes evaluation and/or primary chemoradiation therapy or exclusive chemo-radiation based on an individual patient’s characteristics.
Staging for vulvar cancer follows the International Federation of Gynecology and Obstetrics (FIGO) and and the TNM classification, which are closely aligned.
Both staging systems are mainly based on the pathological report, but in a clinical routine it is necessary to achieve an adequate estimation of the disease to better tailor the treatment plan.
Although imaging is not an integral part of the vulvar cancer FIGO staging, imaging performs an important role and MRI is the imaging modality of choice, as was recently published on the vulvar cancer staging guidelines by the Female Pelvic Imaging Working Group of the European Society of Urogenital Radiology (ESUR).
Due to its superior tissue resolution, MRI is usually requested to better define the size of the tumor and its anatomic extension to the adjacent structures including the superficial (labia majora, minora, clitoris) and the deeper ones (urethra, vagina, and anus).
FIGO classificatio FIGO stage I Stage I is defined as a tumour confined to the vulva or perineum without lymph node or distant metastasis.
It is further sub-divided into stages IA and IB according to tumour size and stromal invasion: • Stage IA—Lesions ≤ 2 cm in size with stromal invasion ≤ 1.0 mm. • Stage IB—Lesions > 2 cm in size or with stromal invasion > 1.0 mm.
The role of imaging is limited in stages IA and IB.
Vulvar carcinoma is depicted as a solid mass with nonspecific low signal intensity on T1WI and intermediate to high signal intensity on T2WI.
DCE-MR imaging sequences with early arterial phase tumour enhancement may be useful in the detection of small vulvar lesions (Figure 1).
FIGO stage II Stage II is defined as a tumour of any size with extension to adjacent perineal structures (1/3 lower urethra, 1/3 lower vagina, anus) without lymph node or distant metastasis.
On T2WI sequences, local tumour invasion may be depicted by disruption of the hypointense signal that circumscribes the urethra and/or interruption of the low signal intensity of the vaginal wall or the anal sphincter by an intermediate to high signal intensity tumour.
MRI increases the staging accuracy and can better demonstrate involvement of the urethra, anus, and vagina (Figure 2).
FIGO stage III Stage III represents inguinofemoral nodes involvement irrespective of tumour size or local extension.
It is further subdivided according to the number and size of the lymph nodes involved, as well as the presence/absence of extracapsular spread • Stage IIIA1—1 lymph node metastasis (≥ 5 mm). • Stage IIIA2—1–2 lymph node metastasis(es) (< 5 mm). • Stage IIIB1—2 or more lymph nodes metastases (≥ 5 mm). • Stage IIIB2—3 or more lymph nodes metastases ( 1 cm.
Other features may be helpful, especially when combined irregular contour, round shape, presence of necrosis, loss of fatty hilum, and a ratio of short-to-long-axis diameter ≥ 0.75 (Figure 3).
FIGO stage IV Stage IV comprises locally or regionally advanced disease (IVA) and distant disease (IVB). • Stage IVA1—tumour invades upper 2/3 of urethra and/or vagina, bladder mucosa, rectal mucosa or is fixed to pelvic bone • Stage IVA2—fixed or ulcerated inguinofemoral lymph nodes (Figure 4) • Stage IVB—any distant metastasis, including pelviclymph nodes ESUR guidelines For primary tumours ≤2 cm, confned to the vulva and/ or perineum, and with ≤1 mm of stromal invasion, imaging staging is not recommended.
For tumours >2 cm and ≤4 cm, clinical staging and groin ultrasound (with puncture of suspicious lymph nodes) or MRI staging are both considered valid options.
For local staging of SCC with stromal invasion >1 mm, tumour size >4 cm, or tumours with suspicious involvement of the urethra, vagina, or anus according to clinical evaluation pelvice MRI should be performed.
For regional or locally advanced disease (FIGO stages III–IVA) or suspicious distant metastases (FIGO stage IVB), chest, abdominal and pelvic CT (or PET/CT) with coverage of the inguinal regions should be performed.