Sticky exudative film

Introduction Cryptococcus skin lesions: manifested as papules, blisters, pustules, infectious soft palate-like papules, acne-like pustules; subcutaneous tissue masses, invasive nodules, abscesses, cellulitis, varicella-like rash, carbuncle-like lesions , purple spot, verrucous proliferation, ulcer, etc., no characteristic, the surface can be covered with a sticky exudative film. Cryptococcus neoformans is round or oval in the tissue, with a diameter of 5-12 m, which can retain Gram stain; the cells are wrapped by a wide capsule, no hyphae and spores are formed, and buds are reproduced. According to the capsular antigenicity, Cryptococcus neoformans has four serotypes A, B, C and D.

Cause

[cause]

Cryptococcus neoformans is round or oval in the tissue, with a diameter of 5-12 m, which can retain Gram stain; the cells are wrapped by a wide capsule, no hyphae and spores are formed, and buds are reproduced. Cryptococcus neoformans can easily grow on various media at room temperature or 37 ° C. Colonies can grow in a few days on sand-protected medium, which is milky white and mucus-like.

According to the capsular antigenicity, Cryptococcus neoformans has four serotypes A, B, C and D. Domestically, there are many types of A, followed by type B and type D, and no type C. The capsular antigen can be dissolved in cerebrospinal fluid, serum and urine and can be detected by specific serum. Studies have found that B/C strains are more resistant to 5FC than A/D strains.

[Pathogenesis]

Cryptococcus, which is found in soil and pigeon dung, can be inhaled into the respiratory tract along with dust. The dried cryptococcus is only 1 m in diameter and can enter the alveoli. Cryptococcus is not encapsulated in vitro, and soon after entering the body, the capsule is formed, and the capsular cryptococcus is pathogenic. Cryptococcus that invades the human body does not necessarily cause disease, and cellular immunity plays a major role in preventing cryptococcal infection.

After Cryptococcus invades the lungs, a small number of granulomas form and symptoms appear. Cryptococcus can enter the central nervous system through the blood of the lungs. The reason why the bacteria often invade the central nervous system may be:

1 lack of antibodies in cerebrospinal fluid;

2 lack of complement activation system in cerebrospinal fluid;

3 Dopamine in cerebrospinal fluid is conducive to the growth of cryptococcus.

Cryptococcal meningitis is more pronounced in the skull base pial lesions. The subarachnoid space has extensive exudate accumulation, including monocytes, lymphocytes and cryptococci. Localized granuloma can also be formed, the latter is a strong reaction of the body, composed of tissue cells, giant cells, lymphoid cells and fibroblasts; Cryptococcus is less found, mostly in giant cells and tissue cells. Pathogenic bacteria can also invade the brain parenchyma along the perivascular sheath, causing vasculitis of the brain stem, leading to ischemia and softening of the local brain tissue, and granuloma formation in the brain parenchyma. Cryptococcus can also proliferate in the perivascular space and form many macroscopic cysts in the gray matter, which is filled with cryptococcus.

There are two types of skin lesions, granuloma and glial lesions. The latter has less tissue reaction and contains a large amount of cryptococcus.

an examination

Related inspection

Laboratory tests for fungal infections

Skin mucosal cryptococcosis: 10% to 15% of patients with cryptococcosis develop skin damage. The original hair style is relatively rare, and the subsequent hair style is mostly spread by systemic infection.

(1) Skin damage: manifested as papules, blisters, pustules, infectious soft palate-like papules, acne-like pustules; subcutaneous tissue masses, invasive nodules, abscesses, cellulitis, varicella-like rash, carbuncle-like lesions , purple spot, verrucous proliferation, ulcer, etc., no characteristic, the surface can be covered with a sticky exudative film.

(2) Mucosal damage: often occurs in soft palate, hard palate, tonsil, gingiva, nasal septum or pharynx, maxillary sinus. Spread from the blood line, or caused by skin expansion. It is characterized by nodules, granulomas or chronic ulcers.

Differential diagnosis

Skin cryptococcosis is distinguished from acne, infectious soft palate, skin tuberculosis, sporotrichosis, or malignant tumor by damage characteristics, pathology, and fungal culture.

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