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D T Shum

Publications and source records attributed to D T Shum.

At least 19 recordsLinked to original sources
PubMed2001

Osteoclastic giant cell tumor of the pancreas: case report and literature review.

An unusual case of a 40-year-old woman seeking treatment for a 10-cm cystic neoplasm of the pancreas is described. Imaging revealed a large proteinaceous, fluid-filled cyst with a mural nodule. Laparotomy was successful with en bloc resection. Pathologic examination revealed a neoplastic mucinous epithelial tumor with an abundance of multinucleated tumor giant cells. This presentation is consistent with literature reports of an osteoclastic-type giant-cell tumor of the pancreas. The natural history, pathologic evaluation, and clinical implications of this rare neoplasm are discussed with reference to published reports.

Adult↗
PubMed2000

Sentinel node biopsy in melanoma using technetium-99m rhenium colloid: the London experience.

Nodal metastases in patients with melanoma identify a reduction of survival by 50%; however, elective lymph node dissection (ELND) has not been shown clearly to improve survival. Morton's technique of sentinel node biopsy, using preoperative lymphoscintigraphy and intraoperative blue dye, addresses elegantly the controversy regarding ELND. Sentinel node biopsy has been shown to stage the patient accurately because metastases from melanoma follow an orderly progression from the sentinel node to the remainder of the basin. Fifty-six consecutive patients with American Joint Committee on Cancer stage 1b or 2 melanoma seen at the London Health Sciences Center between July 1998 and January 2000 were enrolled prospectively to undergo sentinel node biopsy. Preoperative lymphoscintigraphy was conducted in the nuclear medicine department. A total of 10 to 15 MBq (0.27-0.41 mCi) of technetium 99m (99mTc) rhenium colloid or filtered sulfur colloid was injected intradermally around the biopsy scar. Images were obtained to localize all draining nodal basins. The location of the sentinel node was marked on the skin. The patient was taken to the operating room and anesthetized. Isosulfan blue dye was injected intradermally around the biopsy scar. A hand-held gamma probe was used intraoperatively as a guide to the first draining node. Blue-stained lymphatic channels aided in the dissection. Sentinel node localization was successful in 55 of 56 patients, for an overall success rate of 98%. Preoperative lymphoscintigraphy identified a sentinel node in an unpredictable location in 32% of patients. On average, 2.3 sentinel nodes per patient were identified on the initial scan, and 2.2 sentinel nodes per patient were recovered at surgery. Both 99mTc rhenium and filtered sulfur colloid showed no substantial differences in tracer uptake and retention in the sentinel node. Twelve patients had a positive sentinel node on routine histology, and 11 patients subsequently underwent completion lymphadenectomy. The mean thickness of the primary melanoma in the 12 patients with positive sentinel nodes was 3.7 mm compared with a mean tumor thickness of 1.8 mm in the remaining 41 patients with negative biopsies (p = 0.0003). Two patients experienced recurrence in a regional basin after negative pathological evaluation of the sentinel node. Reverse transcription-polymerase chain reaction analysis of both of these patients was positive. Two patients are alive with metastatic disease and 54 patients are alive without disease, with a mean follow-up of 1 year (range, 2-24 months). Complications occurred at a substantially higher rate (45%) after completion lymphadenectomy than after sentinel node biopsy alone (9%). Sentinel node biopsy is a feasible technique with a high success rate (98%), but it requires a multidisciplinary approach. This study validates the clinical usefulness of 99mTc rhenium colloid for lymphoscintigraphy.

Adult↗
PubMed1997

Molecular cloning and gene expression analysis of PSP94 (prostate secretory protein of 94 amino acids) in primates.

Prostate secretory protein of 94 amino acids (PSP94) has shown the potential to be a diagnostic biomarker and a therapeutic agent for prostate cancer. Primates have been the main animal models for studying the biology of this molecule. We have cloned and analyzed the cDNA and promoter region of PSP94 from baboon (Papio anubis). Sequence divergence among baboon, monkey, pig, and human, in both the exons and 5'-flanking region indicates rapid evolution of the PSP94 gene. There are conserved steroid hormone response elements (SHRE) in the promoter region of all three primate species. Multiple, alternative transcripts starting near these SHREs and upstream to the TATA box were identified by reverse transcriptase polymerase chain reaction (RT-PCR) and rapid amplification of 5'-cDNA ends (5' RACE) in primate prostatic tissues. This differential transcription initiation may be linked to androgen regulation of PSP94 gene expression. PSP94 transcripts were detected by RT-PCR in a wide variety of mucus-secreting tissues. However, the alternative transcripts were found only in the prostate. The distribution of the PSP94 protein in baboon secretory tissues was also examined by Western blot analysis using a polyclonal antibody against the human homolog. A positive immunoreactive band was detected, but it was weak, due probably to epitope divergence between the two species. In all young, healthy primate animals tested, the level of immunoreactive PSP94 in prostate tissues was lower than expected. In addition, RT-PCR combined with Southern blot analysis on prostate tissues in these animals failed to detect the PSP57 mRNA produced by alternative splicing of PSP94 primary transcript. These observations can be explained by the sexual immaturity and incomplete prostate development in these young primates. This explanation was supported by histological examination of their prostate during PSP94 immunohistochemistry.

Amino Acid Sequence↗
PubMed1996

Proliferating cell nuclear antigen (PCNA); prognostic value in the clinical recurrence of primary basal cell carcinoma.

Proliferating cell nuclear antigen (PCNA) is a nuclear protein which is correlated with the S-phase of the cell cycle and has been utilized by many investigators as a marker of cell proliferation. A previous immunohistochemical study revealed increased PCNA staining in clinically and histologically aggressive basal cell carcinoma and the present study evaluated the prognostic value of PCNA in clinical recurrence of primary basal cell carcinoma. Thirty patients with primary basal cell carcinoma (BCC) treated with shave biopsy followed by electrodesiccation in 1989 and have been regularly followed up for local recurrence were selected for this study. The histology of their primary BCC's was reviewed and the presence of PCNA in the tumor cells was studied immunohistochemically. Ninety-six percent of the non-recurrent BCC's had < 10% of tumor cells showing a positive staining for PCNA whereas 100% of the BCC's that recurred showed more than 30% of tumor cells staining positive for PCNA. In comparison, 88.9% of the non-recurring group showed non-aggressive histological features and only 66.7% of the recurring group was aggressive by microscopic appearance. In summary, the PCNA staining appeared to be superior to traditional histologic features in predicting clinical recurrence in primary BCC's and further prospective studies in a larger patient group are warranted.

Adult↗
PubMed1996

High frequency 40-MHz ultrasound. A possible noninvasive method for the assessment of the boundary of basal cell carcinomas.

BACKGROUND: Ultrasound imaging systems operating close to 20 MHz in frequency have been used to image skin tumors. Ultrasound imaging at 20 MHz has been used to determine the boundaries of basal cell carcinomas (BCCs). An inherent shortcoming of imaging systems operating at these frequencies is their limited resolution. OBJECTIVE: We investigated whether 40-MHz ultrasound imaging could provide higher resolution compared with the lower frequency systems and thus be a superior, noninvasive method of assessing the boundaries of BCCs. METHODS: Nine BCCs from six individuals were examined clinically and ultrasonographically, and then biopsied to confirm diagnosis. The depth of BCCs measured on histological sections was compared with the corresponding value obtained using ultrasound. For this study we required a nonsurgical, nondestructive means of treating BCCs that would allow repeated ultrasound imaging, and therefore topical 5-flurouracil (5-FU) was chosen. Following 5-FU therapy a biopsy was obtained from the site of the treated BCC after ultrasound imaging had been performed. Clinical, ultrasonic and histopathologic evaluation of each BCC was carried out independently by different individuals. At the end of the study all the BCC sites were treated surgically be electrodesiccation and curettage or completely excised. RESULTS: High resolution ultrasound images of BCCs were obtained with agreement between histology and ultrasound findings in all none lesions prior to therapy and in eight of none lesions posttherapy. There was a significant correlation between the depth of BCCs measured histologically and using ultrasound (P = 0.0004, r = 0.92). CONCLUSIONS: This study suggests that 40-MHz ultrasound may provide an estimate of the boundary of a BCC in vivo. High frequency 40-MHz ultrasound imaging may be an adjunct to clinical and histologic evaluation but does not replace the need to obtain tissue for microscopic examination.

Aged↗
PubMed1996

The use of high-frequency ultrasound as a method of assessing the severity of a plaque of psoriasis.

BACKGROUND AND DESIGN: Ultrasound imaging, while initially developed to visualize internal organs, is now being applied to image the skin. In this preliminary study, we used a high-frequency, 40-MHz ultrasound imaging system to provide high-resolution images in psoriasis and examined the relationship between clinical and ultrasound ratings in plaque-type psoriasis. The ultrasound image of a psoriatic plaque demonstrates a superficial echogenic band (band A), followed by a nonchogenic band (band B), and a deeper echogenic band (band C). RESULTS: In psoriatic plaques (N = 145), the severity of the psoriasis as assessed according to the degree of scaling, erythema, and thickness (SET score) correlated best with the width of band B (P < .001, r = 0.86) and less well with the width of bands A (P < .001, r = 0.59) and C (P < .001, r = 0.44). For the treated psoriatic plaques (n = 64), for which paired readings were available before and after therapy, changes in the SET scores correlated best with the change in the width of band B (P < .001, r = 0.96) and less well with the change in the width of bands A (P < .001, r = 0.61) and C (P < .001, r = 0.45). Ultrasound analyses and clinical evaluation were performed by independent raters. CONCLUSIONS: The data suggest that high-frequency ultrasound imaging may prove to be a noninvasive technique that can be used as an adjunct to the clinical evaluation of the lesional severity of psoriatic plaques.

Female↗
PubMed1996

Increased pigmentation in scleroderma.

OBJECTIVE: Increased pigmentation is found in patients with scleroderma (systemic sclerosis, SSc) even in areas that have never clinically been involved with skin thickening. We wanted to determine if the pigmentation is due to subclinical sclerodermatous changes, or a systemic factor such as an increase in adrenocorticotropic hormone (ACTH). METHODS: To determine if clinically uninvolved skin that is pigmented differs from nonpigmented skin, skin biopsies were taken from patients with scleroderma from 2 different sites: (1) from pigmented but otherwise clinically normal skin, and (2) from nonpigmented clinically normal skin adjacent to the first site. Biopsies were examined by a dermatopathologist for evidence of dermal and epidermal changes. Cosyntropin stimulation tests were performed after baseline cortisol and ACTH samples were obtained. RESULTS: Six patients with diffuse SSc (dSSc) and 4 with limited SSc (ISSc) had skin biopsies. Patients with dSSc were more likely than those with ISSc to have increased pigmentation in uninvolved skin. Pigmented skin specimens had either a higher content of epidermal melanin and/or a more severe degree of pigmentary incontinence with a higher number of dermal melanophages in the superficial dermis. The cosyntropin stimulation tests were normal and there were no differences between subjects with diffuse and limited SSc or between those with and without increases in pigmentation. CONCLUSION: Clinically uninvolved skin in many of these patients with SSc was abnormal, and subtle changes of SSc were present, especially in the pigmented biopsies. There was no evidence of adrenal deficiency in these patients. It is difficult pathologically to differentiate the changes in pigmented compared to unpigmented skin in patients with SSc, except for changes of increased melanin and pigmentary incontinence.

Adrenocorticotropic Hormone↗
PubMed1995

Epidermoid cyst of the occipital bone.

This case illustrates the classic presentation, investigation, and management of diploic epidermoid cysts. It is important to consider this condition in the differential diagnosis of a scalp mass that is deep, nonmobile, and in the frontal, parietal, and occipital regions. If suspected, skull radiographs will provide invaluable information, and if a diploic epidermoid cyst is present, they will direct further management.

Adult↗
PubMed1994

Usefulness of the dissecting microscope in the surgical management of skin cancers.

Dermatopathological examination of excised skin cancers serves the dual purposes of defining the nature of the malignancies and evaluating the resection margins for evidence of tumor involvement. Conventional histological techniques, including horizontal frozen sections as prescribed in Mohs micrographic surgery to evaluate resection margins, can often be tedious and not without many pitfalls. In this study, the use of a stereoscopic dissecting microscope is compared with routine microscopy in the examination of 54 skin specimens resected with the clinical diagnosis of cancer. Our results show that the dissecting microscope is more efficient and as accurate in diagnosing basal and squamous cell carcinomas, and in detecting tumor involvement of resection margins. The ability to visualize marginal surfaces in three dimensions allows for a thorough examination and quick localization and mapping of the involved sites. Tissue artifacts due to fixation, freezing, or sectioning are nonexistent. With the lower cost and ease of operation, we suggest that the dissecting microscope is a more superior instrument. Its usefulness in the surgical management of skin cancers should be emphasized and further validated.

Basal Cell Carcinoma↗
PubMed1993

Sarcomatoid renal cell carcinoma. An immunohistochemical study of 18 cases.

Malignant spindle cell neoplasms are a diagnostic challenge regardless of their location. In the retroperitoneum a major consideration in the differential diagnosis is sarcomatoid renal cell carcinoma; if an epithelial component cannot be recognized histologically, special studies may be required to reach the correct diagnosis. In an attempt to better characterize this entity, 23 cases of sarcomatoid renal cell carcinoma (6.3%) were identified from a review of 363 renal cell carcinomas. Blocks were available for immunohistochemical analysis in 18 cases. The epithelial and sarcomatoid portions were studied with a panel of antibodies directed against cytokeratin (AE1/AE3, CAM 5.2, and 34 beta E12), epithelial membrane antigen, Leu-M1, muscle-specific actin, S100 protein, desmin, and vimentin. The epithelial nature of the spindle cell component was best demonstrated by positive reactivity with the anti-cytokeratin AE1/AE3 (in 17 [94%] of the 18 cases). The other epithelial markers stained the spindle cell component less frequently: cytokeratin CAM 5.2 in seven cases (39%); epithelial membrane antigen in nine cases (50%); and high-molecular-weight cytokeratin 34 beta E12 in no cases (0%). In 10 cases (56%) vimentin positivity and in six cases (33%) actin positivity was seen in the spindled areas. The spindle cell component stained for Leu-M1 in four cases (22%) and for S100 protein in one case (6%) and did not react for desmin in any case. From this study we conclude that in the majority of sarcomatoid renal cell carcinomas the epithelial nature of the spindle cells, as indicated by cytokeratin expression, can be documented using immunohistochemical methods.

Carcinoma, Renal Cell↗
PubMed1993

Reduction of sunburn damage to skin by topical application of vitamin E acetate following exposure to ultraviolet B radiation: effect of delaying application or of reducing concentration of vitamin E acetate applied.

The skin of the skh-1 mouse after ultraviolet B (280-320 nm, UVB) irradiation shows the pathological changes typical of sunburn damage: spongiosis (edematous spaces) around some cells, necrosis of keratinocytes, giving rise to sunburn cells, inflammatory infiltration of polymorphonuclear leucocytes, etc. In our previous study, these were accompanied by erythema, increased skin sensitivity, and edematous swelling. The topical application of tocopherol acetate (TA) immediately after the UVB exposure decreased these changes. In this paper, multiple measurements of the skin thickness were made at different locations along the magnetic resonance imaging (MRI) cross-sectional image of the skin. This permits effects to be quantified with (if desired) the contralateral half of the back serving as an internal control, either exposed (positive control) or unexposed (negative control). Topical application of TA resulted in an increase in the concentration of free tocopherol in the skin. No qualitative differences in ultrastructural appearance of the UVB-irradiated, TA-treated skin could be discerned by careful examination. In vivo high resolution video microscopy of blood flow in venules of the irradiated mouse ear revealed a large (tenfold) but not statistically significant decrease in stationary lymphocytes adhering to the venule walls. The delaying of the application of TA up to 8 hours after the termination of UVB irradiation still offered statistically significant protection as did immediate application of 5% TA in diluent Myritol 318 (Delios S, Henkel).

Administration, Topical↗
PubMed1992

Topical tocopherol acetate reduces post-UVB, sunburn-associated erythema, edema, and skin sensitivity in hairless mice.

Exposure of the skin of the back of skh-1 hairless mice to UVB (310 nm peak) irradiation at doses of 0.115-0.23 J/cm2 results after 24-48 h in an erythema which can be quantified using an erythema meter, providing a useful model of sunburn. Application of pure d-alpha-tocopherol acetate, a thick oil, to the skin immediately following the exposure to UVB significantly reduces the increase in erythema index, by 40-55%. At the lower dose (0.115 J/cm2), skin thickness (associated with edematous swelling of the sunburned skin) was measured by a novel non-invasive technique not previously reported for this purpose--magnetic resonance imaging (MRI). In two experiments the UVB-induced increase in skin thickness was significantly reduced at 24 hr by 29 and 54%, and at 48 hr by 26 and 61%. After 8 days the untreated irradiated mouse skin still showed a significant increase in thickness (24%) compared to the untreated unirradiated control, while the treated irradiated control was not significantly thicker than the unexposed control. Skin sensitivity was tested using a modification of the technique of esthesiometry, by observing rapid avoidance responses of the mouse to a pressure of 0.96 g/cm2 exerted by applying to the skin the tip of a nylon esthesiometer fiber extended to 60 mm in length. The untreated irradiated mice were more sensitive (p less than 0.07, Wilcoxon test) than the treated irradiated mice, and also significantly different from the untreated unirradiated control mice (p less than 0.04, Wilcoxon test), but the treated irradiated mice were not significantly differently sensitive when compared to the unirradiated controls (p less than 0.32). Taken together these data indicate that the erythema, edema, and skin sensitivity commonly associated with UVB-induced sunburn are significantly reduced by topical application of tocopherol acetate even after the exposure has occurred. This observation suggests that treatment of sunburn may be possible even after the irradiation has stopped, by a derivative of d-alpha-tocopherol which is stable to autooxidation.

Animals↗
PubMed1992

Small cell carcinoma of the urinary bladder. A clinicopathologic analysis of 22 cases.

Small cell carcinoma of the urinary bladder is an uncommon tumor. The authors report the clinicopathologic findings in a series of 22 cases. Fifteen men and 7 women were studied; their ages ranged from 51 to 87 years (mean, 62.4 years). The most frequent presentation was hematuria (94.4%). At diagnosis, three patients had Stage B disease, six had Stage C, and ten had Stage D (unknown stage in three). Histologically, 6 were oat cell type tumors, 11 were of intermediate cell type, and 5 were of combined cell type. Immunohistochemical studies demonstrated positivity for neuron-specific enolase in ten of ten cases, cytokeratin in seven of ten cases, chromogranin in eight of nine cases, serotonin in seven of nine cases, and S-100 protein in four of ten cases. Neuroendocrine differentiation was seen in five of seven cases examined by electron microscopy. Treatment and follow-up data were available for 19 patients: 10 (52.6%) were dead of disease, 5 (26.3%) were alive and well, 3 (15.8%) were alive with disease, and 1 (5.3%) died of an unrelated cause. The 2-year survival rate was 50% for patients with Stage B, 25% for patients with Stage C, and 33% for patients with Stage D disease. Although overall survival was poor, some cases responded well to therapy. Based on the authors' experience, radical cystectomy with adjuvant chemotherapy appears to be the treatment of choice.

Aged↗
PubMed1991

Paraganglioma of the urinary bladder: immunohistochemical, ultrastructural, and DNA flow cytometric studies.

Primary paraganglioma arises infrequently in the urinary bladder. We present the clinicopathologic, immunohistochemical, ultrastructural, and DNA flow cytometric findings in three cases (one man and two women). Ages at diagnosis were 19, 35, and 45 years. One female presented with paroxysmal headaches and hypertension that followed urination; the remaining two patients presented with hematuria. Immunohistochemical studies revealed positive reactivity for chromogranin (three patients), met-enkephalin (three), leu-enkephalin (three), vasoactive intestinal polypeptide (two), serotonin (one), and S-100 protein (one; sustentacular cells only). Neurosecretory granules were identified in all cases; in the patient with hypertension, the granules were small with eccentric cores similar to those of adrenal pheochromocytomas. A nondiploid DNA flow cytometric pattern was present in all three patients, an aneuploid pattern was present in two, and a tetraploid pattern was present in one. After diagnosis, one patient was alive without progression at 7 years, one died of an uncertain cause at 5 years, and one suffered multiple recurrences over a 24-year period before developing metastatic disease. While the presence of aneuploidy has been shown to be a predictor of malignant behavior in adrenal pheochromocytomas, our study illustrates that DNA ploidy cannot be used as a diagnostic criterion for malignancy in urinary bladder paraganglioma.

Adult↗
PubMed1991

Azygos vein laceration due to blunt trauma.

The azygos vein ascends along the thoracic spine through the mediastinum and drains into the superior vena cava at the level of the fourth thoracic vertebra. Fracture-dislocation of the mid-thoracic spine, as a result of blunt thoracic trauma, can tear the azygos vein. Four such fatal cases (three motor vehicle accidents and one fall) were studied, only one of which was recognized prior to death. The vein can also be torn, in the absence of skeletal injuries, by horizontal acceleration/deceleration forces. The pathologist must consider azygos vein laceration as a possible cause of either hemothorax or hemomediastinum or both in a victim of a blunt chest trauma, if that individual had persistent hypotension during the few hours before death and no identifiable source of hemorrhage can be found postmortem in sites such as the heart, great vessels, lung, and chest wall. A fracture-dislocation of the thoracic spine may not necessarily be present. Azygos vein laceration seems to be an uncommon cause of hemothorax and hemomediastinum; however, this injury is probably more frequent than is implied by the few cases described in the medical literature.

Accidental Falls↗
PubMed1990

Metastatic Crohn's disease. Case report and review of the literature.

Metastatic Crohn's disease is an unusual granulomatous inflammation of the skin that is noncontiguous to the gastrointestinal tract. Our review of the English-language literature shows that 23 cases of metastatic Crohn's disease have been published since its description in 1964. The skin lesions can be in the form of erythematous nodules, plaques, or ulcers, and the lower extremities are involved in half of the cases. We describe a 24-year-old woman with metastatic Crohn's disease. Ultrastructural examination revealed changes that were compatible with episodic endothelial cell injuries. Results of both direct and indirect immunofluorescence studies were negative. The possible role of T lymphocytes and macrophages in mediating this vascular damage is considered.

Adult↗
PubMed1990

Usefulness of immunoperoxidase staining with high-molecular-weight cytokeratin in the differential diagnosis of small-acinar lesions of the prostate gland.

There are a number of benign, small-acinar lesions in the prostate gland that may be difficult to differentiate from small-acinar adenocarcinoma. An important diagnostic criterion in this differentiation is the loss of the basal layer in small-acinar adenocarcinoma and its preservation in benign conditions. A monoclonal antibody to high-molecular-weight cytokeratins (34 beta E12) has been shown to stain these basal cells preferentially. To assess the usefulness of this antibody in distinguishing benign from malignant small-acinar lesions, we examined 21 cases of small-acinar adenocarcinoma and 47 examples of benign lesions, which included atypical adenomatous hyperplasia, atrophy, post-sclerotic hyperplasia, basal cell hyperplasia, and fibroepithelial nodule. Positive staining with 34 beta E12 was seen in 13/13 cases of atypical adenomatous hyperplasia, although in some cases the staining was weak and focal. Positivity with 34 beta E12 was also demonstrated in all other benign lesions studied. All 21 cases of small-acinar adenocarcinoma showed no reactivity with 34 beta E12. The results suggest that 34 beta E12 is of value in distinguishing between well-differentiated, small-acinar prostatic adenocarcinoma and its mimics. However, care is needed in interpretation of staining in formalin-fixed material due to the variable reactivity, particularly in cases of atypical adenomatous hyperplasia.

Adenocarcinoma↗