Changes in the epidermis serve as important histopathological clues to the diagnosis of skin disorders. These peculiar changes are referred to as epidermal reaction patterns. Certain epidermal reaction patterns such as acantholytic dyskeratosis, epidermolytic hyperkeratosis, cornoid lamellae and papillomatosis point towards a specific diagnosis and hence it is important to recognise them. In this article, we have reviewed the histopathological appearance of these reaction patterns as well as their etiology and the conditions in which they are seen.

Background: Histopathology is considered the gold standard for diagnosis of basal cell carcinoma (BCC) but is time consuming and needs expertise to make a correct diagnosis. On the other hand, Tzanck test is a simple, easy, inexpensive and rapid test which uses exfoliative cytology to make a diagnosis. Objective: To compare the results of Tzanck test with histopathology in the diagnosis of BCC and to evaluate the diagnostic reliability and accuracy of Tzanck test in BCC. Materials and Method: Twenty-six patients with clinical suspicion of BCC were recruited. Samples for Tzanck test and histopathology were taken and diagnoses made independently. Results of Tzanck test were compared with histopathology. Results: Twenty-three cases were histopathologically proved to be BCC. Tzanck test correlated in 12 cases of BCC and could exclude all three non-BCC lesions. In 11 cases it failed to diagnose BCC. The sensitivity and specificity of Tzanck test were 52.2% and 100%, respectively, and positive and negative predictive values were 100% and 21.4%. Conclusion: Tzanck test can be recommended for initial, rapid evaluation of a clinically diagnosed case of BCC. Under experienced hands, it reliably confirms BCC. The limitation is low negative predictive value. Since it does not give information about subtypes of BCC which is of great value in therapeutic planning, histopathological confirmation is mandatory.

Dermatofibrosarcoma protuberans (DFSP) is a fibro-histiocytic tumor of intermediate malignant potential. Unusual morphologic patterns can be misleading. Sarcomatous change in DFSP is a rare occurrence. Presence of Verocay bodies and myxoid change in DFSP is uncommon. We report a case where the trucut biopsy was initially reported as neurogenic tumor based on prominent Verocay bodies, myxoid change and increased mitoses. Resection specimen had classic areas of DFSP with foci of Verocay bodies, prominent myxoid change, myofibroblastic differentiation, sarcomatous transformation and a satellite nodule. We also briefly discuss the relevant literature.

A rare and probably the first documented case of isolated cutaneous toxoplasmosis is being reported in a 50-year-old, vegetarian, immunocompetent man. The granulomatous nodule located on the scrotal skin was excised, and the sections and crushed material of the nodule were subjected to different staining techniques. Demonstration of crescentic structures and PAS-positive material confirmed the presence of Toxoplasma gondii. The significantly raised titer of anti-toxoplasma antibodies further supported the diagnosis. The case was successfully managed surgically. No further treatment was advised since the patient was immunocompetent and it was assumed that cell-mediated immunity would further control the proliferation of organisms.