Sarcoptes scabiei in histopathologic sections of skin in human scabies.

The usual methods of diagnosis remove Sarcoptes scabiei from its habitat. Thus, one has no appreciation of the host-endoparasitic interaction, especially the pathologic response of the surrounding tissue and the means by which the mite survives and lives its life cycle in the skin. The biopsy specimen described in this article demonstrates the tissue reaction that can be correlated with clinical symptoms. It also clearly depicts the actual position, morphological features, and developmental cycle of the mite in the skin.

Tinea faciei in infants caused by Trichophyton tonsurans.

Tinea faciei has been observed periodically in children, however, it is a relatively rare occurrence in infancy. We examined three infants with tinea faciei caused by Trichophyton tonsurans. Two of the patients were potassium hydroxide (KOH) negative for fungal hyphae but culture positive, while the third was both KOH and culture positive. Trichophyton tonsurans was isolated from the scalp of family members in two of the three infants.

Dual infection of the toe web caused by Trichophyton rubrum and Microsporum canis.

A case of tinea pedis caused by a dual infection with Trichophyton rubrum and Microsporum canis is reported. It is of particular interest because infections of the toe webs caused by M. canis are uncommon and the combination of T. rubrum and M. canis has not been reported. In addition, a marked difference in response to treatment with an imidazole (bifonazole) was observed.

Tinea capitis caused by Trichophyton tonsurans.

Children with tinea capitis caused by Trichophyton tonsurans often have a lifetime of association with the organism and, in spite of intermittent therapy, as adults pass the infection to successive generations. While most current treatment regimens are directed at treating the individual patient, our study supports the need to evaluate and possibly treat all family members and their home environment.

The cotton swab technic for the culture of dermatophyte infections--its efficacy and merit.

A set of three comparison studies under varying conditions was performed to determine the efficacy of a cotton swab technic for obtaining material for culture of dermatophyte infections. Matched fungal cultures, one by swab and one by scrape, on each of 110 subjects showed that there was no difference in the two methods. The merits of this culture technic are explored and the conclusion is drawn that the cotton swab is an efficient and reliable adjunct to the practice of dermatology.

Spreading pigmented actinic keratosis.

We present four cases of spreading pigmented actinic keratoses, an only recently described pigmented lesion of sun-exposed areas, in which the histologic appearance is that of actinic keratosis with the additional feature of excessive melanin deposition in the lower epidermis and in the upper dermis. Clinically, it is a brown patch or plaque with a smooth surface, usually larger than 1 cm, that tends to spread centrifugally. Clinical differential diagnoses include seborrheic keratosis, melanocytic nevus, senile lentigo, lentigo maligna, and lentigo maligna melanoma. This pigmented lesion is probably much more common than the existing literature would indicate.

Unstained negative image patterns. A checkpoint for quality slides.

Before stains were available, pathologists had to rely on unstained sections viewed through crude microscopes, but they still were able to make diagnoses and discoveries. Unstained sections may still be used to advantage in making diagnoses of skin lesions quickly, accurately, and easily on the basis of negative image patterns. Low-power scanning by conventional microscopy of freshly cute and mounted, still wet, paraffin sections of skin specimens enables the histotechnologist and dermatopathologist to accomplish three things: 1) to check orientation of the sections at an early stage, 2) to cut complete sections, and 3) to find the area or areas of pathology to cut. Furthermore, because diagnoses can be made from unstained sections, extra cuts for special stains may be ordered in advance of routine staining. The dermato-pathology laboratory is able, therefore, to produce slides of better quality and diagnoses more accurately and quickly.

Laboratory alert: clues to the identification of dermatophytes as the etiologic agents of subcutaneous abscesses.

Trichophyton mentagrophytes was isolated on blood agar and in thioglycollate broth after prolonged incubations of four and seven days, respectively, of a routine bacterial culture taken from a subcutaneous abscess on the inner thigh of a 24 year old woman. The lesions had been present on both thighs for six months before correct diagnosis and treatment. Attention is called to the importance of clinical history to the alert microbiologist in determining the correct diagnosis of such lesions when the original bacterial culture reveals no growth after 48 hours.