PubMed Health⌕ Search

Biomedical subjects

S F Cramer

Publications and source records attributed to S F Cramer.

At least 37 records · Page 2Linked to original sources
PubMed1991

The mystique of the mistake. With proposed standards for validating proficiency tests in anatomic pathology.

Variability in classification in anatomic pathology does not necessarily indicate that a mistake has been made. It is usually an artifact, created when pathologists choose a single category from among two or more justifiable alternatives. This is most common when standard classifications with uniform terminology are not used. It also can occur when classification systems are not constructed so as to insure mutual exclusivity of categories. It is proposed that a proficiency test in anatomic pathology should not be considered scientifically valid until a professional organization primarily concerned with anatomic pathology has endorsed its proposed classification system as having categories that are close to 100% mutually exclusive in the hands of expert pathologists not involved in developing the system. All possible precautions should be taken to insure that the "right answers" for any proficiency test are generated in a way that excludes the possibility of multiple justifiable alternatives.

Clinical Competence↗
PubMed1991

The origin of epidermal melanocytes. Implications for the histogenesis of nevi and melanomas.

Among the most venerable concepts in dermatopathology is Unna's 19th century notion of Abtropfung, ie, that melanocytes drop off from the epidermis to the dermis during the histogenesis of melanocytic tumors. Paradoxically, however, Unna's basic premise of an epidermal origin for melanocytes has been seriously questioned for over 40 years, based on experimental evidence favoring a neural crest origin for melanocytes. Recent work has strengthened the evidence for a neural crest origin of epidermal melanocytes, and it has been suggested that the concept of Abtropfung be replaced by the concept of Hochsteigerung. The concept of Hochsteigerung holds that melanocytes migrate up from the dermis into the epidermis-not only in normal development, but also during normal tissue maintenance. It now seems likely that the precursor of melanocytes, in both normal and abnormal differentiation, may not be a melanoblast (a primitive cell committed to melanocytic differentiation) but rather a pluripotential cell. Although axon-investing Schwann cells have been the traditional focus as the closest relative of the epidermal melanocyte, recent studies suggest that another nerve sheath cell, the perineural cell, might be a better candidate. These concepts have profound implications for the histogenesis of melanocytic nevi and melanomas.

Animals↗
PubMed1990

The frequency of uterine leiomyomas.

As a leading cause of hysterectomy in premenopausal women. uterine leiomyomas are a major public health problem. However, very little work has been done on their epidemiology. Indeed, their true frequency has never been established using systematic and meticulous methods. In this study, gross serial sectioning at 2-mm intervals was applied as an adjunct to routine pathology processing in 100 consecutive total hysterectomy specimens. This tripled the number of leiomyomas noted in routine pathology reports. There were 649 leiomyomas in 77 of 100 uteri, with multiplicity of leiomyomas in 84%. Although leiomyomas were more numerous and larger in women with a clinical diagnosis of myomatous uterus, the incidence was no higher than in uteri removed for other reasons. The postmenopausal incidence of leiomyomas was no lower than the premenopausal incidence, although postmenopausal leiomyomas were smaller and fewer. These findings suggest that epidemiologic studies of leiomyomas may not be valid if they are based only on clinical diagnoses or routine pathology reports.

Adult↗
PubMed1989

Signet-ring squamous cell carcinoma.

Among carcinomas, signet-ring morphologic characteristics have been regarded as pathognomonic of adenocarcinoma. This report presents the case of a poorly differentiated cutaneous squamous cell carcinoma with a monodispersed, invasive signet-ring component. Kreyberg stains had negative results for mucin. Immunohistochemical analysis demonstrated that concentric rings in the signet-ring cells were composed of keratin. To the best of the authors' knowledge, this is the first report of signet-ring squamous cell carcinoma. Another feature that bears emphasis is that this squamous cell carcinoma led to the death of the patient, even though it originated in a field of actinic keratosis.

Adenocarcinoma, Mucinous↗
PubMed1989

Impact of diagnostic immunohistochemistry on the recognition and management of two cases of thyroid cancer with protracted courses.

This report presents two cancer cases with protracted courses in which diagnostic immunohistochemistry for thyroglobulin and/or calcitonin was performed several years after the original light microscopic interpretation. In both cases, diagnostic immunohistochemistry suggested significant changes in tumor classification. In light of current controversies and interpretive problems in this area, confirmatory tests for serum calcitonin and serum thyroglobulin and scans for iodine 131 uptake were performed. These confirmed the immunohistochemical evidence, and led to major changes in patient management. Several similar cases were found in the literature. In cancer cases with a protracted course, but with atypical or discordant clinical and/or pathologic features, diagnostic immunohistochemistry for thyroid markers may merit consideration because of the potential for meaningful changes in clinical management.

Adenocarcinoma↗
PubMed1988

Benign glandular inclusions in parotid nerve.

Benign salivary ductular and acinar structures were demonstrated within an enlarged, disorderly intraparotid nerve in association with a mucoepidermoid carcinoma that did not, itself, manifest perineural invasion. Salivary gland can thus be added to the growing list of tissues in which "perineural invasion" by noncancerous epithelium has been observed. The proliferative features of the neural tissue in this case support the notion that neural elements may play an active role in the establishment of intimate neural-epithelial relationships. The mechanism for this phenomenon in the present case is postulated to be proliferation and ingrowth of the nerve tissue, possibly mediated by nerve growth factor or some related substance.

Aged↗
PubMed1988

The melanocytic differentiation pathway in congenital melanocytic nevi: theoretical considerations.

It is suggested that the melanocytic series is characterized by a differentiation pathway (MDP) that has four discrete stages during normal development and in postnatal tissue maintenance--nerve sheath precursor (nsp), dermal migratory, junctional migratory, and dendritic--and that congenital melanocytic nevi (CMN) derive from cells in the nsp stage of the MDP. This concept accounts satisfactorily for morphologic variations and clinicopathologic correlations in CMN. It also permits a unified explication of both similarities and differences between congenital and acquired melanocytic nevi (AMN), which are thought to arise by transformation of nsp cells in the MDP during postnatal tissue maintenance. This perspective suggests that answers to many basic questions about CMN may require meticulous study of the interrelations of CMN with peripheral nerve elements. Such research may be necessary to resolve current controversies about optimal criteria for distinguishing small CMN from AMN, thereby permitting an accurate assessment of the risk of malignant melanoma in association with small CMN.

Cell Differentiation↗