Panniculitis is the inflammation of subcutaneous fat. It poses a diagnostic challenge, both for the clinician as well as the histopathologist owing to its diverse etiologies, overlapping morphological features, and dynamic nature of the lesions. The standard protocol for histopathologic diagnosis is to examine deep skin biopsies after staining with hematoxylin and eosin. Sometimes, however, special stains are also needed to rule out varied etiologies. A thorough histopathologic examination in conjunction with appropriate clinical details is the key to identify different subtypes of panniculitis. In this review, we discuss the classification of panniculitis with salient histopathologic features of the subtypes in each category. We also present a diagnostic algorithm for arriving at a definitive histopathologic diagnosis of different panniculitis subtypes.

Inflammatory dermatoses are interpreted by pattern recognition. Primary perforating disorders including reactive perforating collagenosis, elastosis perforans serpiginosa, perforating folliculitis, and Kyrle's disease show clinical and histopathological overlap. This article highlights the importance of architectural based analysis by “silhouette” observed under scanning magnification for diagnosis of primary perforating disorders.

Introduction: Neutrophilic dermatosis (ND) is a heterogeneous group of diseases with various etiologies and clinical presentations. NDs may clinically present as papule, vesiculopustule, plaque, and nodule of the skin, but they all share the common feature of neutrophilic predominance in the skin. Histological examination of patients with suspected ND is a key step for making the proper diagnosis. Patients and Methods: The aim of this article was to investigate histopathological aspects of different NDs. We obtained our data from medical records of patients at Razi dermatology hospital, between 2012 and 2014. Thirty-eight biopsy records coded under the term of any ND, including Sweet's syndrome (SS), pyoderma gangrenosum (PG), skin lesions of Behcet's disease, neutrophilic drug eruption, amicrobial pustulosis of the folds, pustular vasculitis of the hands, and undetermined ND were recruited in our study. The specimens were evaluated regarding inflammatory reaction pattern, epidermal/adnexal changes, and dermal changes. Results: Most common NDs in our study were PG (42.1%) followed by SS (21.1%). The most common pattern of inflammatory reaction was superficial perivascular and interstitial dermal inflammation in 44.7% of the patients. Exocytosis of neutrophils into epidermis, hair follicle, and eccrine gland was seen in 71%, 18.5%, and 28.9% of the specimens, respectively. Ulceration was only seen in ten PG specimens. Dermal fibrosis and vascular proliferation were reported in all PG patients. Conclusion: The prevalence of some histopathological findings in different types of ND was significantly different. These features seem helpful in distinguishing between different NDs.

Introduction: Forkhead box protein 3 (Foxp3+) regulatory T-cells (Treg cells) are essential to maintain balance between pro- and anti-inflammatory responses. They play a role in maintaining homeostasis by locally suppressing other skin-resident T-cells thus protecting against autoimmune reactions. Thus, they have been the focus of authors' attention in skin T-cell-mediated diseases in the last decade. The Foxp3 gene encodes a transcription factor thought to be important for the function of Treg cells and represents a reliable marker. Contradictory results have been reported in literature about Treg cell densities in the skin of different inflammatory dermatoses including psoriasis, eczema, pityriasis lichenoides chronica (PLC), and cutaneous lupus erythematosus. Patients and Methods: This was a cross-sectional study on lesional skin biopsies from 10 cases of psoriasis, 10 of spongiotic dermatitis, and 16 cases of lichenoid dermatoses (10 of PLC and 6 of discoid lupus erythematosus. We compared the densities of Foxp3+ Treg cells in relation to CD4+ cells in the epidermis and dermis between these groups using Foxp3 and CD4 monoclonal antibodies.Results: Epidermal Foxp3+ CD4+ Treg cells were lower in psoriasis and lichenoid groups than spongiotic group and dermal Foxp3+ CD4+ Treg cells were lower in psoriasis than lichenoid and spongiotic groups. Conclusions: Treg cells have been proved to suppress other skin-resident T-cells and prevent autoimmunity. Being an autoimmune inflammatory dermatosis, psoriasis showed an overall lower density of Foxp3+ CD4+ Treg cells than spongiotic or lichenoid dermatitis. This supports the theory of Treg cell consumption in psoriatic skin due to conversion to interleukin 17 producers.

Background: Obtaining deeper sections or step sections is a common practice for small skin biopsies. Much of the available literature highlights the importance of step sections in neoplastic diseases of skin. However, the routine dermatopathology practice in developing countries shows a predominant burden of nonneoplastic diseases, and the utility of step sections in this context has not been much reported. Objective: The study was aimed to evaluate the utility of prospective step sections in routine dermatopathology practice. Materials and Methods: The present study comprising 200 consecutive skin biopsies was carried out in a prospective manner. Three slides were prepared in each case: Slide 0 was prepared from the ribbon of tissue obtained from untrimmed block, step sections 1 and 2 were obtained at 50 μm and 100 μm depth, respectively. The diagnosis was rendered on slide 0 and subsequently reviewed after examining step section 1 and 2. Results: Of the 200 cases, additional findings on step sections were found in 18 cases (9%) which led to change in diagnosis in 10 (5%) cases. Step section 1 led to correct diagnosis in 6 cases (3%). Step section 2 led to correct diagnosis in 10 cases (5%); however, this was statistically not significant (P ≥ 0.065) when comparing to step section 1. Additional findings which led to diagnosis was most commonly found in the cases of borderline tuberculoid leprosy (5 out of 10 cases) followed by bullous disorders. Conclusion: We therefore believe that step sections improve the diagnostic accuracy in skin biopsies and they are, especially useful in suspected cases of Hansen's disease. There is no statistical advantage of step section 2 versus step section 1; although, step section 2 had shown to include all the additional findings which led to a change in diagnosis.

Context: Immunofluorescence (IF) is an immunological technique which is used for identifying antibodies against antigens that are bound to tissues or those circulating in body fluids. This study is an attempt to evaluate the dermatological lesions such as noninfectious vesiculobullous lesions, connective tissue disorders, vasculitis, and lichen planus using histopathology techniques and direct IF (DIF) studies. Furthermore, an attempt was made to evaluate the diagnostic utility of the IF technique in our hospital. Aims: (1) To determine the utility of IF in the diagnosis of skin lesions. (2) To correlate IF with histopathological findings. Settings and Design: A cross-sectional, observational study. Subjects and Methods: The present study was conducted in the Pathology Department, Coimbatore Medical College, Coimbatore, from August 2012 to August 2013. Fifty cases received during the period were included in our study. Two skin biopsies for each case - one in formalin for routine histopathological examination and other in phosphate buffer solution for IF studies - were received. Statistical Analysis Used: Fisher's exact value, mean, and coefficient of mean were calculated. Results: The lesions were diagnosed by both light microscopy and IF study. Out of fifty cases, 42 cases were positive with the IF technique and the overall sensitivity of IF was 84% in our study. When histopathological and IF findings were correlated, statistically significant two-tailed P = 0.0130 was obtained. Both light microscopic findings and IF findings complemented each other in our study. IF proved to be a necessary supplementary technique to both clinical and histopathological examinations, especially in cases of diagnostic dilemmas. Conclusions: IF is a rapid diagnostic procedure. IF was useful in early diagnosis, treatment, and monitoring of various disorders in our study. Positive and negative DIF had prognostic significance in certain cases. Clinicopathological correlation along with DIF studies proved to be a powerful tool in definite diagnosis of the skin lesions.

Sebaceous carcinoma (SC) of the eyelid is an aggressive, rare tumor of epidermal appendages, accounting for <1% of all cutaneous malignancies. We report a histopathologically diagnosed case of SC, who presented with multiple swellings on the scalp and cervical lymphadenopathy after surgery and radiotherapy. Fine needle aspiration revealed clusters and dispersed population of cells with high nucleo-cytoplasmic ratio, round to oval nuclei, prominent nucleoli, with moderate to abundant vacuolated cytoplasm. A diagnosis of sebaceous gland adenocarcinoma was given. Smears from the lymph node showed features of metastatic carcinoma. This case highlights that fine needle aspiration cytology is a simple, cost-effective tool for diagnosis of SC and can help in early diagnosis.

Eccrine spiradenoma is an uncommon benign tumor of the sweat glands, most frequently characterized by a solitary, painful, deep-seated nodule. A case of multiple spiradenomas in a zosteriform distribution involving three dermatomes is described with its clinico-pathological features.