Direct immunofluorescence demystified: Essential insights and recent advances for dermatologists.

Direct immunofluorescence (DIF) is widely used in dermatopathology for the diagnosis of autoimmune blistering diseases (AIBDs), cutaneous vasculitis, and connective tissue disorders. Although it is easy and useful to perform, it needs technical expertise and experience for proper interpretation. The yield of DIF depends on multiple factors including the adequacy, transportation, storage, processing, and interpretation of the biopsy specimen. Effective collaboration between the dermatologist and dermatopathologist along with meticulous clinico-pathological correlation is crucial for accurately interpreting DIF in the appropriate clinical context. In this narrative review of DIF in dermatology, we discuss the indications of DIF, recent updates on the selection of optimum biopsy sites, basic techniques of DIF including the classical transport medium and its alternatives, processing and staining technique, patterns in various diseases, advancements such as serration pattern analysis, and latest recommendations on the use of DIF in cutaneous disorders.

Clinicopathological Appraisal of Cutaneous Cysts: A 2-Year Retrospective Observational Study.

Background: Cysts, primarily epidermal and trichilemmal, are commonly seen in clinical practice. Rupture, infection, inflammation, and rarely malignant transformation may complicate the cysts. This study aims to analyze the clinicohistological features of cutaneous cysts. Materials and Methods: A retrospective review of patients with the diagnosis of cyst confirmed on histopathology over the past two years (2020-2021) was performed. Clinical details comprised of age, gender, site of involvement, size, duration, and associated symptoms. Histological examination included cyst wall lining, type of keratinization, complications like rupture, inflammation, foreign body giant cell reaction, calcification, and malignant change. Results: A total of 324 cases with mean age of 37.9 years and equal gender distribution were identified. Most frequent diagnosis was epidermal cyst in 89.8%, followed by trichilemmal cyst in 8.9% of cases. Rare types included follicular hybrid cyst, verrucous cyst, vellus hair cyst, and steatocystoma. Most common complication was cyst rupture in 54.3% of epidermal cysts. Proliferating epidermal and proliferating trichilemmal cysts were noted in one and two cases, respectively. Two cases revealed malignancy arising in the wall of epidermal cyst. Limitations: The retrospective study design and non-availability of follow-up data, especially for proliferating cysts and cysts with malignant transformation were the main limitations of this study. Conclusion: Histopathologic examination of excised cutaneous cysts is paramount in reaching accurate diagnosis of the type of cyst and associated secondary changes to enable appropriate management.

Primary cutaneous large B cell lymphoma masquerading as lupus vulgaris.

Primary cutaneous large B cell lymphoma, leg type is a rare and aggressive variant of cutaneous B cell lymphoma. It predominantly affects elderly women, with the lower limb being the most common site of presentation. The overall prognosis is poor, compared to other cutaneous B cell lymphomas. A 47-year-old man presented with a progressively enlarging nodule over the medial aspect of the left foot since 2 months. Clinical examination revealed a nodular plaque-like lesion with central ulceration that measured 7 × 7 cm, firm in consistency, and with ill-defined margins. The initial clinical diagnosis was lupus vulgaris. An incision biopsy was done, which on histopathology and immunohistochemistry revealed a rare diagnosis of primary cutaneous B cell lymphoma, leg type. The patient was started on chemotherapy; however, he succumbed to his illness about 1 year after the initial presentation. It is a rare type of cutaneous lymphoma, which may masquerade infectious disorders such as lupus vulgaris. A detailed histopathological and immunohistochemical analysis is essential for its correct diagnosis and management. Only a handful of cases of this rare condition are reported to date. This case has been reported in view of its rarity and unusual clinical presentation.

Clinicopathological Concordance in 2216 Cases of Skin Biopsy over One Year: An Indian Experience.

Introduction To determine the spectrum of diseases and the level of clinicopathological concordance in skin biopsies received over a period of one year. Methods A total of 2216 skin biopsy cases received over a period of one year at a tertiary care center were retrospectively analyzed. The cases were further divided into further categories in levels of concordance based on the agreement between the clinical and histopathological diagnosis rendered. Results Of the cases, 61.01% showed clinicopathological concordance. Cases with a descriptive pathological diagnosis, not matching the clinical diagnosis, constituted 31.54%, whereas 4.02% of cases had a definitive pathological diagnosis, which was discordant with the clinical differentials; 3.29% biopsies were inadequate. Conclusion This study highlights the clinicopathological concordance in all the biopsies received from dermatology. It emphasizes the importance of skin biopsies in arriving at the diagnosis. However, it is a tool that must be used judiciously. Skin biopsies are also pivotal in flagging malignancies that may mimic benign lesions.