Lichenoid dermatoses involving the vulva: A clinical-pathologic correlation✰

Vulvar Lichenoid Dermatoses With Emphasis on the Distinction Between Lichen Sclerosus and Lichen Planus: A 10-Year Study

OBJECTIVES

Lichen planus (LP) and lichen sclerosus (LS) are the most common vulvar lichenoid dermatoses. The diagnostic challenges are due to site-specific variation in microscopic appearance and small-sized biopsies. Authentication of diagnostic criteria to distinguish LS and LP to uncover any resemblance or divergence in presentation of these conditions is attempted.

METHODS

Cases of vulvar LP and LS diagnosed between January 2012 to December 2022 were included. The clinical details included age, presenting symptoms, examination findings, and other organ involvement. Histopathological analysis of epidermal, dermal, and adnexal findings was done.

RESULTS

There were 28 cases of vulvar LP and 72 cases of LS, with a median age of 51 and 60 years, respectively. Depigmentation and atrophy were the major clinical features in LS, whereas ulcers/erosions and erythema were more prevalent in LP with a significantly higher incidence of oral involvement. The most diagnostic feature in LS was diffuse dermal sclerosis (76.8%) and interstitial pattern of inflammation (81.4%), whereas the characteristic features in LP cases was a lichenoid pattern of inflammation (85.7%), necrotic keratinocytes, and lymphocytic exocytosis. In 44.4% of LS, unconventional features like compact orthokeratosis, parakeratosis, thickened/wedge-shaped hypergranulosis, and sawtooth rete pegs were noted. Lichen sclerosus with lichenoid inflammation (21.4%) mimicked LP, from which it was distinguished by presence of thickened or diminished granular layer with basal melanin absence (60%) and dermal homogenization (80%).

CONCLUSION

Although the classical, well-established variant of LS poses no diagnostic difficulty, the unconventional variant may mimic LP. Identification of the subtle histological clues demonstrated in this study can help to arrive at the correct diagnosis.

Vulvar Lichen Planus Presenting as Chronic Vulvar Purpura

Background: There is a broad spectrum of vulvar pigmented lesions that differ based on their histopathological and clinical features. Chronic vulvar purpura is a rare entity, associated with a broad morphological spectrum, from lichen aureus, Zoon's vulvitis, pigmented purpuric dermatosis and with lichen planus as in our case. Case presentation: In this article we discuss a case of an 86-year-old white woman with hyperpigmentation on her upper vulva, next to the introitus, with complaints of urine incontinence. Biopsy revealed subepithelial stromal lichenoid inflammatory infiltrate containing plasma cells, lymphocytes and some neutrophilic granulocytes as well as dilated and congested vessels. Hemosiderin deposits and erythrocyte extravasation were found. There was evidence of hyperkeratosis with hyper granulosis and erosions. Spongiosis was also noted. Few melanocytes were identified with no sign of malignancy. These findings correlate with the diagnosis of vulvar lichen planus. Conclusions: Chronic vulvar purpura is a clinical term used for different chronic inflammatory dermatoses presenting as red bluish or violaceous discolorations on the vulva, often associated with cayenne-pepper-like speckling. Considering a great overlap of possible diseases, the final diagnosis could be challenging. It is important to exclude a melanocytic tumour in these cases.

Evaluation of Immunohistochemical Markers, CK17 and SOX2, as Adjuncts to p53 for the Diagnosis of Differentiated Vulvar Intraepithelial Neoplasia (dVIN)

Histological diagnosis of differentiated vulvar intraepithelial neoplasia (dVIN), the precursor of human papillomavirus (HPV)-independent vulvar squamous cell carcinoma (VSCC), can be challenging, as features of dVIN may mimic those of non-dysplastic dermatoses. To aid the diagnosis, p53-immunohistochemistry (IHC) is commonly used, and mutant expression patterns are used to support a histological diagnosis of dVIN. However, a proportion of dVIN can show wild-type p53-expression, which is characteristic of non-dysplastic dermatoses. Furthermore, recent research has identified a novel precursor of HPV-independent VSCC—the p53-wild-type differentiated exophytic vulvar intraepithelial lesion (de-VIL). Currently, there are no established diagnostic IHC-markers for p53-wild-type dVIN or de-VIL. We evaluated IHC-markers, cytokeratin 17 (CK17), and SRY-box 2 (SOX2), as diagnostic adjuncts for dVIN. For this, IHC-expression of CK17, SOX2, and p53 was studied in dVIN (n = 56), de-VIL (n = 8), and non-dysplastic vulvar tissues (n = 46). For CK17 and SOX2, the percentage of cells showing expression, and the intensity and distribution of expression were recorded. We also performed next generation targeted sequencing (NGTS) on a subset of dVIN (n = 8) and de-VIL (n = 8). With p53-IHC, 74% of dVIN showed mutant patterns and 26% showed wild-type expression. Median percentage of cells expressing CK17 or SOX2 was significantly higher in dVIN (p53-mutant or p53-wild-type) and de-VIL than in non-dysplastic tissues (p < 0.01). Diffuse, moderate-to-strong, full epithelial expression of CK17 or SOX2 was highly specific for dVIN and de-VIL. With NGTS, TP53 mutations were detected in both dVIN and de-VIL. We infer that immunohistochemical markers CK17 and SOX2, when used along with p53, may help support the histological diagnosis of dVIN.