Reversible effects of permeation enhancers on human skin.

This study outlines a systematic approach for investigating a desired characteristic of chemicals used to facilitate the permeation of drugs across the skin that is, the reversibility of the permeation enhancement effect. This implies that the vital skin barrier function is restored and not permanently impaired after the application of these enhancers. The reversible effects of two terpene enhancers, (R)-(-)-carvone and eucarvone, on excised human skin were evaluated by in vitro permeation and extraction studies on normal (untreated) and enhancer-pretreated epidermis, respectively. For the permeation studies on normal epidermis, the donor solutions were the model drug, haloperidol (HP, 3mg/ml), in propylene glycol (PG) with or without 5% (w/v) enhancer and for the extraction studies using epidermis pretreated with enhancer, a solution of HP (3mg/ml) in PG was used. The solubilities of the enhancers in 0.03% lactic acid (receptor solution) and of HP in PG (donor solution) were determined to demonstrate that the sink and saturated conditions were maintained in the respective compartments of the flow-through cells throughout the in vitro experiments. (R)-(-)-Carvone cleared out of the skin faster than eucarvone. This could be due to the 4-fold higher skin permeability of (R)-(-)-carvone compared to that of eucarvone. The amount of HP deposited in the epidermis was much lower in the eucarvone-pretreated epidermis than that pretreated with (R)-(-)-carvone. The permeation profile of HP across the enhancer-pretreated skin was 4-fold greater than in the vehicle alone (control), but similar to that across untreated skin with enhancer present in the donor solution, indicating that permeation across the enhancer-pretreated skin did not change. The enhancing effects of both terpenes on the skin were found to be reversible and the permeability of the skin was left intact after the passage of the drug in the vehicle with these enhancers.

An unusual case of an intramuscular lipoma of the pectoralis major muscle simulating a malignant breast mass.

INTRODUCTION: Intramuscular lipomas of the pectoralis major muscle are rare and may mimic malignant breast tumours. CLINICAL PICTURE: A 58-year-old Chinese woman presented with a 2- year history of an enlarging left breast mass. Clinical examination revealed a palpable hard mass in the left breast. TREATMENT: Standard mammographic views revealed a radiolucent mass deep in the left pectoralis major muscle. The mass was homogeneously hypoechoic with smooth margins on ultrasound. OUTCOME: Surgical excision of the mass was performed. Histological diagnosis was an intramuscular lipoma of the left pectoralis major muscle. CONCLUSIONS: Recognition of the radiolucent density and submammary location of a pectoralis major muscle lipoma is important as it allows the correct diagnosis to be made.

The role of computed tomography in clinically-suspected but equivocal acute appendicitis.

INTRODUCTION: To study the role of contrast-enhanced computed tomography (CT) of the abdomen and pelvis in the evaluation of patients with clinically-suspected but equivocal acute appendicitis. METHODS: The medical records of 206 consecutive patients who had CT of the abdomen and pelvis for equivocal signs and symptoms of acute appendicitis were reviewed. 7 mm collimated axial sections from the diaphragm to the iliac crest and 5mm collimated sections of the pelvis with intravenous and oral contrast were obtained. The criteria used to diagnose acute appendicitis were: (a) a thickened appendix of more than 7 mm or (b) inflammatory changes in the periappendiceal fat. The CT findings were correlated with the histological diagnosis at appendectomy. If the CT findings were negative for acute appendicitis and surgery not performed, the results were correlated with other corroborating diagnostic investigations or clinical follow-up. RESULTS: A total of 206 patients were scanned, of which 39 were excluded due to lack of any follow-up. Of the final 167 that were studied, there were 36 true positives, 127 true negatives, 4 false negatives and no false positives, resulting in a sensitivity of 93.9 percent, specificity of 100 percent and accuracy of 98.5 percent. CONCLUSION: We have found CT to be a safe, reliable and accurate modality in the diagnosis of acute appendicitis in patients with equivocal presentation.

Clinics in diagnostic imaging (95). Os trigonum.

A 19-year-old boy presented to the Accident and Emergency Department after sustaining trauma to his left ankle and foot while playing soccer. The radiograph of his left ankle showed a well-corticated triangular fragment of bone posterior to the left talus, typical of an os trigonum. This accessory bone was initially mistaken for a fracture fragment and a plaster cast was applied. The term, do not touch lesion, has been coined to describe this group of benign bony entities which may be classified into three broad categories, namely: normal variants, lesions that are real but obviously benign, and lesions that are related to degenerative disease. The importance of recognising the characteristic radiographical appearances of these entities is emphasised, as the need for further imaging or diagnostic tests can usually be avoided.