A morphometric and immunohistochemical study of melanocytes in periorbital hyperpigmentation.

Background: An increase in number of melanocytes in the basal cell layer of the epidermis is an important feature in many disorders of hyperpigmentation. In this study, we attempted an objective evaluation of the linear density of melanocytes and keratinocytes, along with other epidermal characteristics, in periorbital hyperpigmentation using immunohistochemistry and morphometric techniques. Methods: Melanocytes and epidermal parameters were assessed by digital morphometry in 30 newly diagnosed cases of periorbital hyperpigmentation and 14 controls from the post-auricular region. Melanocytes were labelled with the immunohistochemical stains, Melan-A and tyrosinase. We studied the linear keratinocyte density, mean linear melanocyte density, ratio of melanocytes to keratinocytes, the ratio between inner and outer epidermal length, maximum epidermal thickness and minimum epidermal thickness. Results: Melan-A expression of melanocytes showed strong positive correlation (r = 0.883) with the tyrosinase expression. Mean linear melanocyte density was 24/mm (range: 13–30/ mm) in cases and 17/mm (13–21/mm) in controls and this difference was statistically signifi cant (P < 0.001). The mean ratio of melanocyte to keratinocyte was 0.22 (0.12– 0.29) in cases and 0.16 (0.12–0.21) in controls; again, this difference was statistically signifi cant (P < 0.001). There was a mild negative correlation with linear keratinocyte density (r = −0.302) and the ratio between inner and outer epidermal length (r = −0.456). However, there were no differences in epidermal thicknesses. Limitations: There were fewer control biopsies than optimal, and they were not taken from the uninvolved periorbital region. Conclusion: Mean linear melanocyte density and the ratio of melanocytes to keratinocytes is increased in cases with periorbital hyperpigmentation. It is, therefore, likely that increased melanocyte density may be the key factor in the pathogenesis of periorbital hyperpigmentation.

ALK negative inflammatory myofibroblastic tumor of the orbit: A masquerading entity.

Infl ammatory myofi broblastic tumor is a biologically distinct neoplasm of intermediate grade, which can aff ect every possible tissue of the human body. It is a ‘masquerading tumor’ as the presenting complaints vary with the aff ected site. Occurrence of this tumor as an orbital mass is rare and is challenging for both the clinician as well as the pathologist, due to a varied number of lesions sharing a similar picture clinically and histologically. We discuss a rare case of inflammatory myofibroblastic tumor presenting as an orbital mass and the importance of immunohistochemistry in arriving at the diagnosis, which helps dictate the treatment and prognosis of the patient.

Morphometric study of microvessels, epidermal characteristics and inflammation in psoriasis vulgaris with their correlations.

Background: Vascular proliferation, inflammation and epidermal changes are important features in the pathogenesis of psoriasis. Aims: In this study we attempted an objective evaluation of these parameters using morphometry. Methods: Inflammation, microvessels and epidermal parameters were assessed in 50 newly diagnosed cases of psoriasis vulgaris (between 01 Nov 2008 and 31 Oct 2011) by morphometry. Parameters studied were microvessel density, microvessel caliber, inflammatory cell density in dermis, ratio between inner and outer epidermal length, maximum epidermal thickness, minimum epidermal thickness and difference between maximum epidermal thickness and minimum epidermal thickness. Results: Microvessel caliber showed moderate correlation (r = 0.645) and microvessel density, weak correlation (r = 0.226) with inflammatory cell density in dermis. Both these parameters also showed mild positive correlation with "ratio between inner and outer epidermal length". All parameters except minimum epidermal thickness showed mild positive correlation with inflammatory cell density in dermis. Conclusion: All microvessels and epidermal parameters showed positive correlation with dermal inflammation; and epidermal parameters exhibited positive correlation with micro-vascular dilation. It is likely that inflammation is a key factor in the pathogenesis of psoriasis.

Low apoptotic index & bak expression in EBV-associated childhood classical Hodgkin lymphoma.

Background & objectives: Association of Epstein-Barr virus (EBV) with Hodgkin lymphoma (HL) is particularly high in low-income countries, and resistance to apoptosis might play a role in pathogenesis and survival. Data from previous studies are not consistent, and none is available in children. Thus this study was undertaken on Indian children with classical Hodgkin lymphoma to assess the significance of bcl-2, bak and p53 expression, and apoptotic index in relation with EBV status and treatment outcome with chemotherapy alone. Methods: Children (age<15 yr) with classical HL (n=143) were included in the study. Bcl-2, bak, p53, Ki67 and latent membrane protein-1 (LMP1) were detected by immunohistochemistry in pre-treatment lymph node biopsies. Apoptotic index was assessed by TdT-dUTP nick-end labelling (TUNEL). Results: Bcl-2, bak, p53 were expressed above positivity threshold in 83.3, 94.0 and 7.1 per cent of the cases respectively. More than 10 per cent of apoptotic tumour cells were seen in 60.4 per cent of the cases. 131 (91.6%) cases were EBV associated. EBV-positive cases had a significantly lower mean bak expression (p=0.001) and a lower apoptotic index, without higher proliferation index. Advanced stage showed a borderline association with bcl-2 expression in >25 per cent of tumour cells and p53 negative tumours. In univariate analysis, p53 positive cases, which were significantly associated with B symptoms, had a poorer overall survival (P=0.03) while low proliferation index was associated with poorer failurefree survival. Neither EBV status nor any of the apoptotic parameters studied showed independent association with survival. Interpretation & conclusion: EBV detection in children with classical Hodgkin lymphoma was associated with significant lower bak expression and with lower spontaneous apoptosis of H-RS cells suggesting that EBV-LMP1 might downregulate bak pro-apoptotic protein. this needs to be substantiated further.