#dermpathJC March 2021 summary

#d ermpathJC March 2021:

Thursday, March 25th, 9pm EST

Article discussed: Vulvar dermatoses: a histopathologic review and classification of 183 cases

Authors: May P. Chan, MD, and Mary Jane Zimarowski, MD

Temporary free access courtesy of: The Journal of Cutaneous Pathology, https://onlinelibrary.wiley.com/doi/10.1111/cup.12541

Summary prepared by: Haneen Salah, MD (@Hansalah)

Journal Club Summary:

Introduction:

Vulvar dermatoses often pose challenges in classification due to histopathologic overlap. This study documents a single institution experience in diagnosis of vulvar dermatoses, with focus on the frequencies of these conditions as well as detailing subtle histopathologic differences that can aid in either making a diagnosis or narrowing down a differential.

The International Society for the Study of Vulvovaginal Disease (ISSVD) has established a classification system to better aid the diagnosis and to unify terminology used by both dermatopathologists and gynecologic pathologists.

Summary of current study methodology and results:

A total of 188 vulvar biopsies signed out between 2006 and 2010 were reviewed. Five of the cases were excluded due to infectious causes. The remaining 183 cases were analyzed. The average age of the patients was 53.6 years.

Lichen sclerosus (LS) was the most common diagnosed vulvar dermatosis (38.8%). Next most common diagnosis was lichen simplex chronicus (LSC) at 29% and eczematous dermatitis (23%), subtyped into allergic contact dermatitis, irritant contact dermatitis and eczema nos. Zoon’s vulvitis was rarely diagnosed (15%).

Discussion points:

Keeping a broad differential diagnosis is crucial. While there are some dermatologic conditions limited to vulvar skin, there are many dermatoses that can be seen there and are not restricted to the genitalia.

Commonly a multifactorial condition affects the vulvar skin. The most common scenario is LSC superimposed on LS or eczematous dermatitis and even lichen planus. Diagnosing the specimen with LSC should not stop there and careful examination of the underlying dermis is recommended to investigate a primary dermatosis with overlying LSC.

LS was the most common diagnosis in this cohort of patients, which could be as a result of clinicians having a lower threshold to biopsy patients with LS.

Lichen sclerosus (LS): Lichenoid interface dermatitis is a notable early change. Thickened basement membrane can be seen and highlighted with a PAS stain. Wiry fibrosis with lymphocyte entrapment seen at the inferior edge of the subepithelial sclerosis is a useful feature to diagnose LS. This study noted that almost half of the cases had scattered eosinophils, and the presence of eosinophils should not preclude a diagnosis of LS.

Lichen simplex chronicus (LSC): Squamous mucosa and skin affected by LSC may appear quite similar. While vertical fibrosis may be commonsly seen in skin affected by LSC elsewhere, in the vulva, the authors’ experience for vulvar LSC is presence of prominent fibroblasts and zones of pale epithelium. These pale cells resemble “pagetoid dyskeratosis,” and are thought to be clones of keratinocytes that proliferate as a result of chronic friction.

Eczematous (spongiotic) dermatitis: Presence of spongiosis, presence of intraepithelial neutrophils and necrotic keratinocytes were clues for Irritant Contact Dermatitis (ICD) and presence of intraepithelial eosinophils (eosinophilic spongiosis) was a clue for Allergic Contact Dermatitis (ACD). Some cases with overlapping features were commonly signed out as eczema NOS.

Zoon’s vulvitis (ZV): Typical findings include band-like plasma cell infiltrate, often an eroded surface, intraepithelial neutrophils, extravasated erythrocytes and hemosiderin deposition. Considerable difficulty in diagnosis of Zoon’s vulvitis exists particularly when the classic features are not present. Some report presence of “lozenge-shaped” keratinocytes and fibrosis. The authors in this study report a new clue for the diagnosis of Zoon’s vulvitis; basal keratinocytic crowding which was seen in 86.7% of the ZV cases. This feature may be helpful in differentiating from early LS.

Lichen planus (LP): This study reported lower number of LP cases and a reliable feature to differentiate LP from LS was not identified. However a thickened basement membrane highlighted with a PAS stain and decreased elastic fibers highlighted with an elastic EVG stain may help diagnosis of early LS over LP.

Infections: Most commonly overlooked infections in the vulva were erythrasma caused by C. minutissimum and herpetic infection. Careful examination of all deeper sections is advised.