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Biomedical subjects

L Michaels

Publications and source records attributed to L Michaels.

At least 37 records · Page 2Linked to original sources
PubMed1996

Benign mucosal tumors of the nose and paranasal sinuses.

The histogenesis of benign mucosal tumors of the nose and paranasal sinuses is reviewed in this report. In contradistinction to the view favored in the literature, these comprise three distinct entities. Everted and cylindric cell papillomas are true papillomas, lined by stratified squamous and microcyst-laden, columnar, and oncocytic epithelium, respectively. Inverted papillomas are polyps with marked, patchy squamous metaplasia in ductal and surface epithelium and numerous microcysts containing macrophages in those epithelia. Low-grade squamous carcinoma of the nose and paranasal sinuses may be difficult to distinguish from inverted papilloma. There are no intermediate forms from any one of the three types of benign mucosal tumors of the nose and paranasal sinuses to another. The site of origin of everted papilloma is from the nasal septum or nasal vestibular epithelium. Inverted and cylindric cell papillomas arise on the other hand from the lateral wall of the nose, ethmoid, or maxillary sinuses. Inverted papillomas alone among the three have a strong tendency to recur, and some cases are associated with carcinoma, although the development of malignancy is unusual.

Biopsy↗
PubMed1995

Histological study of oxalosis in the eye and adnexa of AIDS patients.

Review of a series of 98 eyes removed at autopsy from 86 AIDS patients identified 12 cases (14%) showing varying degrees of microscopic calcium oxalate deposition. The oxalate crystals were birefringent using polarisation microscopy and were stained histochemically by the silver nitrate-rubeanic acid method (Yasue), a stain considered to be specific for calcium oxalate. In two cases, the deposition was extensive and involved the surface of the ciliary processes, ciliary body and pars plana of the retina, the retinal and optic nerve blood vessel wall, a few retinal pigment cells, and the anterior inner sclera. A lesser degree of intraocular involvement was observed in the remaining 10 cases. In all but two eyes, where a peripheral active area of cytomegalovirus retinitis was present, no other significant microscopical abnormality was found. Clinically, these patients were asymptomatic. At autopsy, oxalate deposits were found in the kidney and/or thyroid in seven of the patients.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Histogenesis of papillomas of the nose and paranasal sinuses.

OBJECTIVE: To determine by review of their histogenesis whether papillomas of the nose and paranasal sinuses are three distinct entities or, as has been favored in the literature, three variations of a single entity. METHODS AND PATIENTS: We examined biopsy sections from 191 patients with sinonasal papillomas. Biopsy sections included all types of sinonasal papillomas stained using routine methods and, in some cases, using immunohistochemistry for macrophages (PG-M1) and proliferation antigen (MIB-1). Two cases of inverted papilloma were also examined using transmission electron microscopy. RESULTS: Everted and cylindric cell papillomas are true papillomas, lined by stratified squamous and microcystladen, columnar, oncocytic epithelium, respectively. Inverted papillomas are polyps with marked, patchy squamous metaplasia and numerous microcysts containing macrophages in ductal and surface epithelium. There are no intermediate forms from any one of the three types to another. CONCLUSIONS: Some differences between the three types are already established with regard to sites of origin, tendency to recur, and association with malignancy. It is likely that their etiologies--eg, concerning human papillomavirus infection--will be found to differ, if their distinct histogeneses are considered.

Humans↗
PubMed1994

Polymerase chain reaction amplification of herpes simplex viral DNA from the geniculate ganglion of a patient with Bell's palsy.

Bell's palsy is the most common cause of facial paralysis. In this study, we demonstrate the presence of herpes simplex viral type 1 (HSV-1) genomic DNA in the geniculate ganglion of a patient who had Bell's palsy. This association suggests that in this patient, HSV-1 may have caused Bell's palsy. If HSV-1 is a cause of Bell's palsy, treatment with acyclovir may be beneficial. Additional studies should be done to establish the prevalence of HSV-1 as an etiologic agent of Bell's palsy.

Aged↗
PubMed1994

Effect of craniotomy and cerebrospinal fluid loss on the inner ear. An experimental study.

Craniotomy with cerebrospinal fluid (CSF) suction was performed on 18 guinea pigs to determine the effects on the inner ear morphology. Six control animals received anaesthesia only and 12 were operated on with a postoperative survival time of 1 or 24 h. The histologic examinations showed no signs of endolymphatic hydrops or injury to other structures in any of the animals. In 11 of the operated animals, red blood corpuscles were demonstrated in the perilymphatic space of the cochlea, the subarachnoid space, and the cochlear aqueduct (CA). After 1 h survival time blood had entered primarily the basal part of the scala tympani, but in the animals of 24 h survival time the blood was more abundant in both the scala tympani and the scala vestibuli indicating flow within the inner ear. The CA thus provides a pathway between the CSF and the whole of the perilymph through which noxious effects could take place.

Animals↗
PubMed1994

The ear in the acquired immunodeficiency syndrome: I. Temporal bone histopathologic study.

A postmortem histopathologic investigation of temporal bones of patients with the acquired immunodeficiency syndrome (AIDS) was performed after microslicing, acid decalcification of the slices and paraffin embedding. Histopathologic changes in 49 temporal bones from 25 patients included severe otitis media in five patients (20%), low-grade otitis media in fifteen (60%), labyrinthine cryptococcosis in two, Kaposi's sarcoma deposit in the eighth nerve of one, and cytomegalovirus (CMV) inclusion-bearing cells in the inner and middle ear of six (24%). It was possible to identify the CMV genome by in situ hybridization in only two bones and expression of CMV antigen by immunohistochemistry in none, probably because of prolonged decalcification in acid. The ear is no less susceptible to AIDS-associated diseases than any other organ, and is particularly prone to CMV infection.

AIDS-Related Opportunistic Infections↗
PubMed1994

Cochlear dysplasia and meningitis.

Congenital dysplasias of the labyrinth of the inner ear are associated with varying degrees of hearing loss. There is a risk of a fistulous communication between the subarachnoid space and the middle ear cavity in some cases that present either as cerebrospinal fluid otorhinorrhea or as recurrent attacks of meningitis. The types of deformity where such a fistula is likely have not been clearly defined. The authors correlated the hearing state with the imaging assessment in 20 patients with congenital malformation of the labyrinth and, in particular, the cochlea. In addition the postmortem histologic findings from one patient with severe cochlear dysplasia who died from otogenic meningitis are described. The key to the assessment is the basal turn of the cochlea. If the basal turn is present and of normal caliber then some hearing is possible and there is no risk of a major fistula. However, if the basal turn is wider than normal or replaced by an undeveloped sac then there is anacusis and very real risk of fistula. In such cases the deformed labyrinth needs to be packed with fibrofatty tissues after just one attack of meningitis.

Adolescent↗
PubMed1993

Keratosis of the tympanic membrane and deep external auditory canal. A defect of auditory epithelial migration.

We have previously described the pathways of movement of epithelium on the tympanic membrane, showing that there are two discrete and separate zones. Four cases of keratosis of the tympanic membrane and deep external auditory canal are here reported. All patients complained of tinnitus and other aural symptoms. Sequences of otoscopic photography of daubs of dye placed on the tympanic membrane showed an abnormal anterior movement over the whole tympanic membrane in two cases and complete paralysis of movement in the two others. These findings suggest that the disorder arises from damage to basal epidermal cells caused by inflammation, which is probably due to infection. Treatment is by suction-stripping of keratin from the eardrum. Careful examination of the eardrum under magnification is required in all cases of tinnitus so as to detect this condition.

Aged↗
PubMed1993

Congenital cerebrospinal fluid fistula through the inner ear and meningitis.

Congenital deformities of the labyrinth of the inner ear can be associated with a fistulous communication between the intracranial subarachnoid space and the middle ear cavity. We describe seven such cases, six confirmed by high resolution CT and one by postmortem histological section. The seven patients all presented with meningitis although a cerebrospinal fluid fistula was demonstrated at subsequent surgery or postmortem. The lesions were bilateral in three patients, unilateral in three and probably bilateral in the postmortem case although only one temporal bone was obtained. In every case there was a dilated sac instead of the normal two and a half turn cochlea on the affected side and this was confirmed at surgery. The demonstration of the basal cochlear turn is of paramount importance in any deaf child presenting with meningitis. A true Mondini deformity with a normal basal turn and some hearing is not at risk of developing a fistula.

Adult↗
PubMed1993

Fatal keratitis ichthyosis and deafness syndrome (KIDS). Aural, ocular, and cutaneous histopathology.

We report a case of KID (Keratitis, Ichthyosis, and Deafness) syndrome in which the patient died at the age of 2 months. Detailed histological study of the affected organs, particularly the inner ear and external auditory meatus, was performed. This case is the first in which previously described principles relating to the biology of the ear canal epithelium have been applied to a patient with skin disease affecting this area.

Deafness↗
PubMed1993

Structure and origin of middle ear corpuscles.

The incidence, origin, structure and composition of middle ear corpuscles (MEC) were studied by dissection microscopy, by special stains and immunocytochemistry of histological sections and by transmission electron microscopy. MEC are formed within fibrous bands derived from transparent fibrous sheets which appear mainly in the mastoid antrum in the middle-aged and elderly. MEC are covered by a layer of epithelial cells with a normal basal lamina, and are largely composed of concentric layers of collagen which display alternating positive and negative birefringence. Pulmonary and prostatic corpora amylacea show a similar light microscopical structure and age relationship, but contain amyloid. It is suggested that MEC and the other bodies may be organized foci of epithelial basement membrane expansion perhaps derived from an in vivo counterpart of the "domes' seen in vitro in some monolayer epithelial cultures.

Adult↗
PubMed1993

Myxoma of the maxillary antrum in children.

Myxomas of the maxillary antrum are rare tumours, particularly in childhood. Although circumscribed, they are often more extensive than apparent and so tend to recur despite their benign nature. Myxomas are gelatinous and are composed of stellate and spindle cells embedded in an abundant alcian blue-positive, mucoid stroma in which blood vessels are often scattered throughout the tumour. Three patients with maxillary myxomas, all presenting in infancy or early childhood, are described.

Age Factors↗
PubMed1992

A histologic study of nonmorphogenetic forms of hereditary hearing impairment.

It appears that many forms of syndromic and nonsyndromic hereditary hearing impairment are secondary to either neuroepithelial or cochleosaccular dysfunction. Making this distinction can be difficult in human temporal bone specimens; however, this added knowledge may ultimately provide prognostic and therapeutic information in hearing habilitation. Fundamental studies using animal models of different types of hereditary deafness may also prove useful in this respect.

Adult↗
PubMed1992

Image analysis in the discrimination of verrucous carcinoma and squamous papilloma.

Verrucous carcinoma is a differentiated variant of squamous cell carcinoma and may present diagnostic difficulties as it may be erroneously diagnosed as squamous papilloma. In this study, the sizes of the intermediate cells in these two conditions were measured by means of morphometric analysis. Biopsies from 28 patients with verrucous carcinoma, 25 patients with squamous papilloma, and ten squamous cell carcinomas were analysed. A significant difference was shown (P less than 0.001) by an uncorrelated t-test between verrucous carcinoma and squamous papilloma. The former had a mean cell area of 373 microns 2 and the latter 184 microns 2. Squamous cell carcinomas differed from the other two neoplasms by their large range of cell areas both within and between cases. Thus, image analysis can be of diagnostic help in cases where no firm initial histopathological diagnosis can be obtained. The diagnosis should be made on morphological grounds, but a mean cell area greater than 300 microns 2 supports a diagnosis of verrucous carcinoma whereas an area less than 250 microns 2 supports a diagnosis of squamous papilloma.

Adult↗
PubMed1992

The imaging characteristics of naso-sinus chondrosarcoma.

Eighteen patients with histologically-verified naso-sinus chondrosarcomata are reviewed, emphasizing their CT and MRI appearances. These tumours present with a soft tissue mass expanding and destroying bone and typically (89%) showing areas of nodular or plaque-like calcification on CT. The magnetic resonance characteristics are more specific and when present with the typical CT features are diagnostic of chondrosarcoma. They combine high signal on T2-weighted sequences, with differential enhancement on post-Gadolinium T1-weighted scans. The contrast enhancement is seen at the periphery of the tumour and the central chondromatous core does not enhance. These changes are dependent upon the vascularity of the tissues concerned and have been correlated exactly with the histopathology of the resected tumour specimens.

Adolescent↗