Immunohistochemistry (IHC) is an important diagnostic tool in histopathology. Dermatopathology is a rapidly developing subspecialty of histopathology. Although IHC is not widely used in routine dermatopathology practice, its application is gradually increasing. IHC is used to differentiate two conditions with similar morphology, to confirm a diagnosis as well as to assess prognosis. It is more commonly used for neoplastic conditions like melanocytic, hematolymphoid, and spindle cell tumors, although uses can be very wide. Although IHC can aid in diagnosis, sometimes interpretation can be difficult as there may be overlapping findings. Thus, IHC should not be interpreted in isolation and should be done in the context of clinical and histological findings. In this review, we have discussed the uses of various immunohistochemical markers in dermatopathology in the light of current literature and their clinical relevance.

Context: “Dark circles” are esthetic concerns that can affect individuals of any age, gender, or race. They can be familial, physiological, or associated with various medical illnesses. Aim: To study the clinicopathological correlation of periorbital hyperpigmentation. Patients and Methods: Fifty patients affected with periorbital melanosis (POM) were enrolled for the study after obtaining informed consent. Details regarding history, demographic data, and physical examination of POM were recorded, and a 2-mm punch skin biopsy was taken from the affected skin under local anesthesia and stained with hematoxylin and eosin (H and E), Fontana Masson (Melanin), Perls Prussian blue (Hemosiderin). Results: Twenty-three (46%) patients with POM had history of chronic illness before developing POM; 18% patients were atopic, 16% had jaundice, 18% had associated pigmentary demarcation lines (PDL) of type F and G, 8% had acanthosis nigricans, 22% patients had anemia, 16% patients gave positive family history of POM, and menstrual irregularity was seen in 16%. Histopathology revealed dermal melanin deposition with melanophages along with predominantly increased epidermal melanin and melanin in vellus follicular epithelium. Prussian blue for hemosiderin was negative in all cases. Conclusions: The study has elicited the multifactorial origin of POM; females are affected more than males. Dermal melanin deposition is a constant feature. Hemosiderin is not found in POM. Increased pigmentation of the vellus follicular epithelium is a feature of POM.

Background: The anti-inflammatory, immunomodulatory, and anti-proliferative effects of vitamin D in pathogenesis of autoimmune diseases have been highlighted in recent years but implications of vitamin D deficiency in systemic sclerosis (SSc) remain understudied. Objectives: To evaluate serum vitamin D levels in SSc patients and matched controls. Materials and Methods: Serum vitamin D levels were estimated in 38 (M:F 5:33) patients aged 23–70 years of untreated SSc and age and gender matched healthy controls. Clinical and investigative evaluation for skin sclerosis by modified Rodnan skin score (mRSS), presence of digital ulcers, Raynaud's phenomenon, type of auto-antibodies, systemic involvement, and serum vitamin D levels were performed. Serum vitamin D levels were defined as normal (30–100 ng/ml), insufficient (10–30 ng/ml), and deficient (<10 ng/ml). Results: Serum vitamin D levels (median ± IQR) were 19.5 ± 77.8 ng/ml in 38 patients and 100 ± 31.3 ng/ml in controls each. Vitamin D deficiency in 13 (34.2%) and insufficiency in 10 (26.3%) patients were identified. Only 2 (5.3%) controls had vitamin D insufficiency and the difference was statistically significant (P = 0.001). An inverse relationship was observed between mRSS and serum vitamin D levels. Conclusions: Patients with SSc have significantly lower serum vitamin D levels than healthy controls. Serum vitamin D levels do not correlate well with age, gender, disease duration or its variants, type of auto antibodies, presence of digital ulceration, or systemic involvement but has inverse correlation with skin sclerosis. Better-designed studies will perhaps resolve issues of potential benefits of vitamin D supplementation in modification of disease activity or severity in SSc.

Sarcoidosis is a multisystem disorder with cutaneous involvement with myriad of morphological presentations, often leading to diagnostic dilemma. We report a case of 31-year-old male with peripheral arterial disease who presented with three morphological forms of sarcoidosis simultaneously, namely, papular, psoriasiform, and pigmented purpuric dermatosis-like lesions. Dermatoscopy of cutaneous lesions showed yellow-orange globules, red dots, linear vessels, and white crystalline structures depending on the clinical forms. Histopathology of all three morphological types of skin lesions demonstrated sarcoidal naked granulomas.Sarcoid specific lesions of more than one morphological type presenting in a same patient is rare. Association of peripheral vascular disease with sarcoidosis is also seen rarely.

Eccrine poroma is a benign adnexal tumor that originates from the uppermost portion of the intraepidermal eccrine duct. It usually presents as a solitary tumor. Histopathology shows a monomorphic proliferation of cuboidal cells, which radially extend from the basal layer to the dermis. Here, we present a rare multilesional eruption of eccrine poroma after chemotherapy and bone marrow stem cell transplantation for acute promyelocytic leukemia along with a description of clinical, pathological, and dermoscopic findings.

Palisaded encapsulated neuroma (PEN) is a distinctive benign neural tumor, which usually presents as a solitary skin-colored papule or a nodule. It is a benign lesion and may clinically mimic a cutaneous neurofibroma, melanocytic nevi, or cutaneous schwannoma. Here we report a rare case of multifocal cutaneous PENs and its differentiation from cutaneous schwannomas, which is possible by histopathology.

Dermatofibromas are common lesions of the skin. Although they occur at any part of the body, they are most commonly observed on the lower legs of middle-aged women. The lesion comprises fibroblast-like cells, histiocytes, collagenous tissue, and blood vessels. Many histological variants have been defined based on the ratio of cell components and their location. These variants of dermatofibroma may cause problems during differential diagnosis between benign and malignant mesenchymal lesions of the skin and may lead pathologists to overdiagnose this lesion. Here, we report a case of clear cell dermatofibroma, which is a rare variant of dermatofibroma, together with its diagnostic traps.