Asha Agarwal

Wavelet-based characterization of spectral fluctuations in normal, benign, and cancerous human breast tissues

Fluorescence intensity fluctuations in the visible wavelength regime in normal, benign, and cancerous human breast tissue samples are studied through wavelet transform. The analyses have been carried out in unpolarized, parallel and perpendicularly polarized channels, for optimal tissue characterization. It has been observed that polarized fluorescence data, particularly the perpendicular components, differentiate various tissue types quite well. Wavelet transform, because of its ability for multiresolution analysis, provides the ideal tool to separate and characterize fluctuations in the fluorescence spectra at different scales. We quantify these differences and find that the fluctuations in the perpendicular channel of the cancerous tissues are more randomized as compared to their normal counterparts. Furthermore, for cancerous tissues, the same is very well described by the normal distribution, which is not the case for normal and benign samples. It has also been observed that, up to a certain point, fluctuations at larger scales are more sensitive to tissue types. The differences in the average, low-pass wavelet coefficients of normal, cancerous, pericanalicular, and intracanalicular benign tissues are also pointed out.

Extranodal manifestation of Rosai-Dorfman disease with bilateral ocular involvement

Rosai-Dorfman disease, that is, sinus histiocytosis with massive lymphadenopathy is a benign systemic proliferative disorder of histiocytes. The typical clinical presentation of the disease includes bilateral painless massive lymphadenopathy, fever and polyclonal hypergammaglobulinemia. Extranodal involvement is present in only a few cases and skin lesions are the most common form of extranodal disease. However, purely cutaneous Rosai-Dorfman disease is uncommon. In this study, we describe a 10-year-old child presenting with bilateral ocular involvement.

Congenital granular cell tumor of the alveolar ridge.

Congenital epulis or neonatal granular cell tumor is a tumor whose histogenesis has long been debated. It is dissimilar to other granular cell tumors; the latter having derivation from Schwann cells and hence being S-100 positive. We report a case of congenital granular cell tumor in a newborn female child that was uneventfully operated. The case is reported here because of its rarity.

Small-cell neuroendocrine tumor of larynx: A rare presentation

Neuroendocrine tumors of the larynx are extremely rare and represent < 1% of all primary laryngeal tumors. We report a case of a 55-year-old man who presented to us with laryngeal tumor, histopathological evaluation of which revealed it to be a neuroendocrine tumor. Diagnosis is based mostly on light microscopy and may be supported by special histochemical stains in some instances.

Primary orbital non-Hodgkin's lymphoma

Non-Hodgkins lymphoma (NHL) can have extra-nodal presentation in approximately 25% of cases unlike Hodgkins lymphoma which rarely involves extra-nodal sites. Extra-nodal lymphoma in the head and neck region is extremely rare. We report a case of 6-year-old girl who presented with medial canthus mass with proptosis, lagophthalmos and no significant loss of vision. CT findings showed an extra-conal homogenous mass lesion in the left orbit along superior and medial orbital wall with extensive destruction of surrounding tissue. Histological sections showed polymorphous population of atypical lymphoid cells accompanied by plasma cells, eosinophils and proliferation of small blood vessels with plump endothelial cells. A diagnosis of NHL was rendered. Further, immunohistochemistry confirmed the lesion as peripheral T-cell lymphoma. The lesion was aggressive in course and the patient succumbed within one-and-half  months of diagnosis.

Experimental and theoretical investigation of fluorescence photobleaching and recovery in human breast tissue and tissue phantoms

Photobleaching and recovery of 488-nm excited fluorescence from resected human breast tissue samples have been studied. Profiles of photobleaching decay were seen to be faster in cancerous tissue than in those of the normal tissue. The reverse behavior was observed in profiles of recovery after photobleaching. A theoretical model based on one-dimensional diffusion theory has been developed to provide insight into the phenomena of fluorescence during photobleaching and recovery in a multiply scattering medium such as tissue. To understand photobleaching and recovery with the help of this theoretical model, we carried out experiments with model media that were prepared with authentic fluorophores, scatterers, and absorbers. The results of these studies suggest that the fluorescence photobleaching profiles are affected more by the absorption than by the scattering properties of a turbid medium such as tissue. In contrast, the scattering properties of the medium are found to affect the fluorescence recovery profiles to a greater extent. These observations could be related to the observed difference in fluorescence photobleaching and recovery profiles of normal and cancerous breast tissues.

Fluorescence depolarization of normal and diseased skin tissues

Fluorescence spectrum is known to be a sensitive tool for detecting microscopic changes in the environment of fluorophores. Steady state fluorescence spectroscopy has been utilized to probe the environment of these molecules in normal and diseased skin human tissue. For fluorescence polarization spectroscopy of human skin tissues, the sample were excited with a plane polarized 50mW argon ion laser operated at 488 nm and the luminescence spectra were recorded after passing through an analyzer. The spectra were recorded with SPEX 1877E triplemate attached with a cooled PMT and DM3000R data acquisition system. The polarized fluorescence spectra of cancerous human skin tissue is different from normal human tissue. The maxima of the spectra of normal and cancerous human tissue are located around 540 nm and 530 nm respectively. The main feature of the computed anisotropy at different wavelengths is the higher value of degree of anisotropy of cancerous tissue compared to the normal counterpart. Higher degree of anisotropy of cancerous tissue may imply that the fluorophores are more tightly bound to proteins or are in a more viscous environment.

Fluorescence study of normal, benign and malignant human breast tissues

Fluorescence properties of flavins in normal, benign and malignant human breast tissues have been investigated between 500-700 nm using 488 nm excitation of an Ar-ion laser. The combination of fluorescence anisotropy and spectral profiles can distinguish normal, benign and malignant from one another. The fluorescence spectra may be characterized by two major bands with the width of the band at 580nm being the distinguishing parameter. The polarization study of human breast tissues shows higher anisotropy for the tumor tissues compared to their normal counterparts. The effects of multiple scattering on depolarization of fluorescence is confirmed by polarization measurements on thin tissue sections which show higher anisotropy values compared to the thick samples. An important observation is the increase in the difference of anisotropy values between some of the normal and malignant tumor samples while going form thick to thin tissues.

Cytomorphological features of lymphoepithelial carcinoma of submandibular gland in an adolescent male

A case of lymphoepithelial carcinoma (LEC) occurring in right submandibular gland of a 13-year-old Indian male is presented, wherein the lesion unveiled itself only after multiple fine needle aspiration (FNA) procedures. This unusual neoplasm has high frequency of occurrence in Eskimos and a predilection for the parotid gland. The aspirates obtained were highly cellular comprising tight clusters of atypical epithelial cells with admixture of lymphocytes. Histopathological examination of the resected submandibular gland and lymph node chain was consistent with the diagnosis of LEC. Immunohistochemistry (IHC) revealed cytokeratin (CK)-positive and S-100-negative tumor cells lying admixed with CD45-positive lymphoid cells. A detailed otorhinolaryngological examination with inclusion of multiple biopsies was found negative for any primary tumor. Although histopathological features of this entity are well established, only a handful of case reports describing cytological features of this entity are present in medical literature. We conclude that the cytomorphological features of LEC are sufficiently distinctive to at least, suggest a possibility of this lesion.

Polarized fluorescence study in human cervical tissue: change in autofluorescence through different excitation wavelengths

This study aims towards applying the intrinsic fluorescence technique, extracted from polarized fluorescence, to detect subtle biochemical changes occurring during the progression of cancer from human cervical tissue samples. The efficacy of this technique, earlier validated through tissue phantoms, is tested in human cervical tissues by comparing the biochemical changes for diagnostic purpose at different wavelengths. It is pertinent to note that the co and crosspolarized fluorescence do not display the high sensitivity obtained through extracted intrinsic fluorescence. We observed that sensitivity and specificity of intrinsic fluorescence technique is high at 325 and 370nm for Collagen and NADH respectively in comparison to 350nm excitation wavelength. It may be concluded that decoupled information at 325 and 370nm wavelengths for collagen and NADH respectively, through intrinsic fluorescence provides better diagnostic parameter for early detection of cervical dysplasia. This information can provide a guiding path for designing a probe for clinical purpose.