Infiltrative-Suppurative, or Zoophilic, Trichophytosis

This form, which is caused by zooanthropophilic fungi, was previously called deep trichophytosis (trichophytia profunda) because the formation of deep suppurative pustules was thought to be its characteristic feature.

An increase in the infiltrative-suppurative trichophytosis morbidity has been registered recently in many countries. Moreover, the role of T. gypseum is outgrowing that of T. faviforme.

Clinical picture and course. Several clinical forms of infiltrative-suppurative trichophytosis are distinguished.

Infiltrative-suppurative trichophytosis of the scalp. In a disease that takes a characteristic course, large solitary foci of affection form. They are sharply circumscribed, hyperemic, considerably infiltrated, and covered with many purulent, succulent crusts. When these crusts are removed, it may often be seen that the pus is discharged from each follicle separately, though at first glance it seems that the patient has a single large and deep-seated abscess; as a result there is another name for the disease, 'follicular abscess'. The pus discharged from each follicle separately resembles honey secreted from the honeycomb. Hence the third frequently encountered name of the disease, kerion Celci (Celsus' honeycomb). In infiltrative-suppurative trichophytosis of the beard and moustache areas (sycosis parasitaria), multiple foci of affection form, which are smaller than those on the scalp but in other clinical symptoms are similar to them.

In zoophilic trichophytosis of the deep form, the infiltrate is very tender to palpation. General symptoms (indisposition, a temperature reaction, headache) and enlargement and tenderness of the regional lymph nodes are frequently encountered. With no treatment applied, the disease resolves in a few months leaving scars or, more often, cicatricial atrophy.

In infiltrative-suppurative trichophytosis of the smooth skin the characteristic lesion is a hyperemic patch, which is strictly demarcated from the surrounding healthy skin, has rounded contours, and is infiltrated and covered with furfuraceous or lamellar scales, there are many follicular pustules and purulent crusts on its surface. The infiltrated patch grows along the periphery to a large size (to a diameter of 5 cm and more) and resolves spontaneously in a few weeks, leaving hyperpigmentation and sometimes cicatricial atrophy. The inflammation and infiltration in zoophilic trichophytosis of the smooth skin, however, just as those in affection of the scalp, may vary in intensity from sharply pronounced (the deep form) to a hardly noticeable superficial form.

Diagnosis. Superficial trichophytosis of the scalp has to be differentiated first if all with microsporosis and favus of the scalp. The decisive factors in the diagnosis of trichophytosis are hairs that have broken off at a low level ('stubs'), a considerable amount of hairs preserved in the foci, no tendency of the foci to merge, and the characteristic localization of the fungal spores inside the hair shaft (endothrix). It should be noted that superficial trichophytosis and microsporosis of the smooth skin share clinical symptoms and microscopic picture in common. The character of the involvement of the hairs (if they are also involved), the medical history (e.g. a sick cat in the family or house), studying the epidemiological situation at the children's establishment, the results of cultural diagnosis, etc. make the diagnosis easier.

The diagnosis of chronic trichophytosis of the scalp is based on the presence of 'dark dots' and atrophic bald areas in the occipital and temporal regions, and the characteristic affection of the nail plates. Foci on the smooth skin are differentiated from erythemo-squamous dermatoses (rubromycosis, psoriasis, etc.).

Trichophytosis unguium is differentiated with rubromycosis, favus, and other diseases of the nails.

Infiltrative-suppurative trichophytosis is differentiated with the infiltrative-suppurative form of microsporosis. The latter is caused by Microsporum lanosum and is relatively rare. In localization of the lesions on the face of men, the disease is differentiated with sycosis vulgaris (staphylococcal), which is usually of a long duration and with no rapidly developing inflammatory phenomena. The follicular character of the lesion and the acute course of the process allow zoophilic trichophytosis to be differentiated from chronic pyoderma and deep mycoses (sporotrichosis, deep blastomycosis, etc.).