Criteria for Risk Stratification of Vulvar and Vaginal Smooth Muscle Tumors

Abstract

Accurate risk stratification of smooth muscle tumors (SMTs) is essential for appropriate patient management. Yet, the rarity of SMTs of the vagina and vulva makes development of a prognostically meaningful classification system challenging. While 2 classification methods for vulvar SMTs and 1 for vaginal SMTs have been proposed, it is our experience that many pathologists tend to apply criteria for uterine SMTs when evaluating vulvovaginal tumors. We retrospectively reviewed a large cohort of vulvovaginal SMTs with clinical follow-up and evaluated which method most accurately classified tumors according to patient outcome. A total of 71 tumors, 53 vaginal (75%) and 18 vulvar (25%), from 71 patients were identified. All tumors were centrally examined for degree of cytologic atypia, morphology (spindled, epithelioid, myxoid), mitotic index per 10 high power fields, atypical mitotic figures, tumor cell necrosis, ischemic necrosis, tumor interface (circumscribed or infiltrative) and margin status. Clinical features were recorded for each patient. Follow-up was available for 63 patients (89%), and ranged from 1 to 234 months (median: 64 mo). While site-specific and uterine criteria showed equally excellent sensitivity in classifying smooth muscle neoplasms as leiomyosarcoma according to patient outcome, uterine criteria showed improved specificity relatively to site-specific methods in classifying tumors as nonsarcoma according to patient outcome. We recommend that uterine SMT criteria and nomenclature be adopted for evaluation and classification of vulvovaginal SMTs.

ALK Immunoexpression is Specific for Inflammatory Myofibroblastic Tumor Among Vulvovaginal Mesenchymal Neoplasms

“…Among smooth muscle tumors of the vulva and vagina, leiomyomas have a well-known propensity to show focal to extensive myxoid stroma, particularly in the setting of pregnancy (26)(27)(28)(29)(30); myxoid stroma can also be seen in STUMP and leiomyosarcoma at this site (26,29,(31)(32)(33)(34). Conversely, IMT, including uterine examples and our case of vulvar IMT, may exhibit variable expression of smooth muscle markers.…”

“…Distinction of vulvar IMT from vulvar smooth muscle tumors is essential for prognostic classification. Vulvar-specific criteria have been proposed for assessing the malignant potential of smooth muscle tumors (26,30,35), although recent studies suggest that uterine-specific criteria may be more useful (31). Proposed prognostic criteria for uterine IMT are based on limited data, which is somewhat conflicting between the two published studies to date (2,6).…”

Primary vulvar extragastrointestinal stromal tumor in a 77‐year‐old woman

“…Despite its rarity, EGISTs should be considered when encountering a cutaneous/subcutaneous spindle cell lesion in the perineal area. The differential diagnosis is broad (Table 2) and includes smooth muscle neoplasms (leiomyoma or leiomyosarcoma), melanoma, sarcomatoid squamous cell carcinoma, other primary cutaneous/subcutaneous mesenchymal neoplasms including vascular, nerve sheath, and fibroblastic tumors 30–34 . A comprehensive immunohistochemical panel can usually lead to the correct diagnosis.…”

“…The differential diagnosis is broad (Table 2) and includes smooth muscle neoplasms (leiomyoma or leiomyosarcoma), melanoma, sarcomatoid squamous cell carcinoma, other primary cutaneous/subcutaneous mesenchymal neoplasms including vascular, nerve sheath, and fibroblastic tumors. [30][31][32][33][34] A comprehensive immunohistochemical panel can usually lead to the correct diagnosis. In the majority of GISTs, the tumor cells show diffuse and strong cytoplasmic expression of T A B L E 1 Pathologic and molecular features of reported vulvovaginal EGISTs.…”

Vulvar Leiomyosarcoma in Pregnancy

“…Leiomyosarcoma is diagnosed when no less than two of the three elements are recognized: mitotic index ≥ 10 per 10 HPFs, moderate to severe cytological atypia, and tumor cell necrosis [14]. Recently Sayeed and colleges [15] found that uterine criteria were as sensitive as and more specific than site-specific criteria. And the current WHO classification applies the same criteria used for uterine SMT [13].…”