TUBERCULOSIS OF THE SKIN
BY Dr.Ahmed Abdul-Aziz Ahmed* WWW.SMSO.NET
Classification Of MycobacteriaMycobacteria are acid-fast, weakly gram-positive, nonsporulating, and nonmotile rods. The family Mycobacteriaceae consists of only one genus, Mycobacteria, which includes the obligate human pathogens M. tuberculosis and the closely related M. bovis, M. africanum, and M. microti as well as M. leprae and a number of facultatively pathogenic and nonpathogenic species .
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Tuberculosis Of The Skin Definition and ClassificationTuberculosis of the skin is caused by M. tuberculosis, M. bovis, and, under certain conditions, the bacillus Calmette-Guerin (BCG), an attenuated strain of M. bovis. Classification according mode of infection or the immunologic state of the host
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* WWW.SMSO.NETEpidemiology And Incidence
the organisms are neither very virulent nor very infectious: about 5 to 10 percent of infections with M. tuberculosis lead to disease . Tuberculosis of the skin also has a world-wide distribution more prevalent in regions with a cold and humid climate in the past, it now also occurs in the tropics. A sharp increase of mycobacterial infection has occurred with increasing migrations and with the advent of the AIDS epidemic, but it has not led to a proportional increase of tuberculosis of the skin.
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The Host The human species is quite susceptible to tuberculous infections, but differences exist among populations and individuals. Populations whose contact with tuberculosis spans many centuries are, in general, less susceptible than those who have come into contact with mycobacteria recently; genetic factors, Age, state of health, and somatic type of the individual are of importance, as are environmental factors. After mycobacteria have invaded the host, they may either multiply and lead to progressive disease or their multiplication is checked or completely arrested. The balance between bacterial'multiplication and destruction is determined not only by the properties of the invading organisms but also by the ability of the host to control such an infection.
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Skin Disease Due To M. TUBERCULOSIS/ Bovls InfectionPrimary inoculation tuberculosis (tuberculous chancre , tuberculous primary combplex The inoculation of mycobacteria into the skin of a host not previously infected with tuberculosis. The tuberculosis chancre and the affected regional lymph nodes constitute the tuberculosis primary complex of the skin.
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Incidence Most patients are children, but adolescents and young adults particularly in people working in professions related to medicine Sites of predilection are the face, hands, and lower extremities, which are readily injured. One-third of the lesions are found on the mucous membranes of the conjunctiva and oral cavity.* WWW.SMSO.NET
Pathogenesis Tubercle bacilli cannot actively penetrate intact skin, they are introduced into the tissue at the site of minor abrasions or wounds. Venereal inoculation tuberculosis may occur in healthy individuals after sexual contact with patients suffering from genitourinary tuberculosis. Lesions in the mouth may be due to bovine bacilli from nonpasteurized milk and occur after mucosal trauma or tooth extraction. The skin lesions appears 2 to 4 weeks after inoculation.and spreads to the regional lymph nodes.* WWW.SMSO.NET
Clinical Manifestations Small papule, scab, or wound with little tendency to heal A painless ulcer develops to attain a diameter of over 5 cm It is shallow with a granular or hemorrhagic base studded with miliary abscesses or covered by necrotic tissue. The ragged edges are undermined and of a reddish blue hue; as the lesions grow older, they become more indurated, with thick adherent crusts* WWW.SMSO.NET
Infections result in painless ulcers or fungating granulomas. Inoculation tuberculosis of the finger may present as painless paronychia; inoculations of mycobacteria in puncture wounds have resulted in subcutaneous abscesses. painless regional lymphadenopathy develops 3 to 8 weeks after the infection cold abscesses may develop with sinuses.
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* WWW.SMSO.NETDiagnosis And Differential Diagnosis - Any ulcer with little or no tendency to heal and unilateral regional lymphadenopathy in a child should always arouse suspicion. - The diagnosis is conformed by bacterial culture.
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PPD is negative in the initial phases but converts to positive during the course of the disease The differential diagnosis : syphilis, cat-scratch fever, sporotrichosis, and ulcerative lesions of other mycobacterioses as well as other foms of skin tuberculosis. Course Without treatment last up to 12 months. lupus vulgaris develops at the site of a healed tuberculous chancre. Ractivation of the disease may occur. Hematogenous spread may give rise to tuberculosis of other organs, particularly of the bones and joints. progress to acute miliary disease with fatal outcome. Erythema nodosum is a feature in approximately 10 percent of the cases.* WWW.SMSO.NET
Tuberculosis Verrucosa Cutis (Warty Tuberculosis) Incidence Pathogenesis Inoculation tuberculosis occurring in persons who have acquired a certain degree of immunity , PPD are highly positive. Sites of minor wounds or abrasions or may occur from the patient's own sputum. physicians, pathologists, medical students, and laboratory attendants, from tuberculous patients or from autopsy material. Children can become infected by playing and sitting on ground contaminated with tuberculous sputum* WWW.SMSO.NET
Clinical Manifestations The hands, in the radial border of the dorsum, and on the fingers. In children: the sites of predilection are the lower extremities The lesions are asymptomatic and start as a small papule or papulopustule with a purple inflammatory halo; they become hyperkeratotic and are often mistaken for a common wart. Slow growth and peripheral expansion lead to the development of a verrucous plaque with an irregular outline and a papillomatous horny surface. Clefts and fissures discharging pus extend into the underlying infiltrated base.* WWW.SMSO.NET
* WWW.SMSO.NETThe evolution of the lesions is slow, and, without treatment, the course extends over many years. Secondary pyogenic infection , lymphangitis , regional lymphadenitis
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Lupus vulgaris is an extremely chronic and progressive form of tuberculosis of the skin occurring in individuals with moderate immunity and a high degree of tuberculin sensitivity Incidence has steadily declined during the past decades Females appear to be affected about two to three times as often as males, and all age groups are equally affected.* WWW.SMSO.NET
Pathogenesis The lesions progress steadily and, although spontaneous involution does occur, new lesions arise within old scars. Lupus vulgaris. originates from tuberculosis elsewhere in the body by hematogenous, lymphatic, or contiguous spread, most often from cervical adenitis or pulmonary tuberculosis.* WWW.SMSO.NET
Clinical Manifestationsusually solitary , asymptomatic macule or papule, characterized by a brownished color and a soft, friable consistency , Progression is characterized by an elevation of the lesions and a deeper brownish color. in patients with active pulmonary tuberculosis, multiple foci may develop 90 percent of patients the head and neck are involved. Lupus vulgaris usually starts on the nose or cheek and slowly extends onto adjacent areas. The earlobes are often affected. diascopy : typical apple-jelly color. Plane forms manifest as flat plaques with a serpiginous or polycyclic outline and a smooth surface.
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Hypertrophic forms appear as soft tumorous growths with a nodular surface ulcerative forms, the underlying tissue may be affected by progressive necrosis. Atrophic scarring, with or without prior ulceration, is a prominent feature of lupus vulgaris. Sometimes, fibrosis is very pronounced and leads to deformations, mutilations and contractures* WWW.SMSO.NET
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Lupus vulgaris of mucous membranesSmall, soft, gray or pink papules, ulcers, or granulating masses that bleed easily , dry rhinitis is often the only symptom of early nasal lupus. Progressive lesions destroy the cartilage of the nasal septum; cicatricial deformities of the soft palate and stenosis of the larynx may also result.
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DiagnosisCriteria helpful in the diagnosis are 1.the softness of the lesions,2.the brownished color,3.and the slow evolution 4.The apple-jelly nodules revealed by diascopy are highly characteristic Histologic examination and a positive culturefor M. tuberculosis/bovis confirm the diagnosis Course Lupus vulgaris is extremely chronic, and without therapy its course usually extends over many years or even decades
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it is progressive and leads to considerable impainnent of function and to disfiguration Contractions result in a reduction of joint mobility, and ulceration and destruction of the cartilaginous structures of the face and scarring lead to cicatricial ectropion with its complications. Microstomia with impainnent of speech and food intake. The most serious complication : of long-standing lupus vulgaris is the development of (carcinoma ).* WWW.SMSO.NET
The Relationship Of Lupus Vulgaris To Tuberculosis Of Other Organs40 percent of patients with lupus vulgaris there is associated tuberculous lymphadenitis 10 to 20 percent have pulmonary tuberculosis or tuberculosis of the bones and joints Scrofuloderma (Tuberculosis Colliquativa Cutis) It is a subcutaneous tuberculosis leading to cold abscess formation and a secondary break down of the overlying skin.
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Pathogenesis It results from contiguous involvement of the skin overlying another tuberculous process: 1- Tuberculous lymphadenitis 2- Tuberculosis of bones and joints 3- Tuberculous epididymitis It affect all age groups, there is a higher prevalence among children, adolescents, and the aged.* WWW.SMSO.NET
Clinical ManifestationsThe parotidal, submandibular, and supraclavicular regions and lateral aspectsof the neck , the lesions are often(bilateral) Lesions on the extremities or on the trunk accompany tuberculous disease of the phalangeal bones , joints, the sternum, and the ribs. A firm subcutaneous nodules freely movable asymptomatic infiltrate. As it enlarges it becomes doughy it takes months before there is liquefaction with subsequent perforation Ulcers and sinuses develop and discharge watery and purulent or caseous material.
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* WWW.SMSO.NETDiagnosis And Differential diagnosis
M. aviumintracellulare lymphadenitis and the more benign M. scrofulaceum Syphilitic gums deep fungal infections ,particularly sporotrichosis Actinomycosis severe forms of acne conglobata hidradenitis suppurativa Course Spontaneous healing does occur , it takes years typical scars permit a correct diagnosis, even after the process has resolved
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Metastatic Tuberculous Abscess (Tuberculous Gumma)Definition And Pathogenesis It is due to hematogenous spread of mycobacteria from a primary focus during a period of lowered resistance, resulting in single or multiple cutaneous and subcutaneous lesions It usually occurs on : Under nourished children of low socioeconomic status Immunodeficient or severely immunosuppressed patients
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Clinical ManifestationsNontender and fluctuant abscesses arise either singly or as multiples on the trunk, extremities, or head ,it forms fistulas and ulcers. Metastatic tuberculous abscesses may occur with progressive organ tuberculosis or in miliary tuberculosis. Diagnosis And Differentialdiagnosis - panniculitis ,deep fungalinfections - syphilitic gumma, and hidradenitis suppurativa
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Orifcial Tuberculosis (Tuberculosis Ulcerosa Cutis et Mucosae) It is rare form of tuberculosis of the mucous membranes and the skin of the orifices due to autoinoculation of mycobacteria from progressive tuberculosis of internal organs. .
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Pathogenesispulmonary, intestinal, or, rarely, genitourinary tuberculosis are the underlying disease is far advanced Mycobacteria shed from these foci in large numbers are inoculated into the mucous membranes of the orifices, usually after trauma positive intradermal tuberculin reaction, but in terminal stages anergy develops
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Clinical Manifestationsthe tongue is most frequently affected, particularly the tip and the lateral margins , but the soft and hard palate are also common sites. oral condition often represents an extension of ulcerative tuberculosis of the pharynx and larynx. In cases with intestinal tuberculosis, lesions develop on and around the anus in females with active genitourinary disease, the vulva is involved
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A small yellowish or reddish nodule appears on the mucosa and breaks down to form a circular or irregular ulcer with a typical punched-out appearance, undermined edges, and soft consistency Its floor is covered by pseudomembranous material and often have multiple yellowish tubercles and eroded vessels. The surrounding mucosa is swollen, edematous, and inflamed. Lesions may be single or multiple and are extremely painful.* WWW.SMSO.NET
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Diagnosis And Differential Diagnosis Syphilitic Lesions aphthous ulcers Carcinoma
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Acute Miliary Tuberculosis of the Skin (Tuberculosis Cutis Miliaris Oisseminata) Definition And Pathogenesisextremely rare skin manifestation of fulminating miliary tuberculosis due to hematogenous dissemination of mycobacteria. The initial focus of infection is either meningeal or pulmonary, and the disease may follow infections such as measles and HIV.
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Clinical ManifestationsIt occurs on all parts of the body, particularly on the trunk. Minute erythematous macules , papules and purpuric lesions. Sometimes vesicles with central necrosis and crust develop.
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Diagnosisindividuals already gravely ill and, because of the severity of the underlying process, often goes unnoticed diagnosis is usually substantiated by the evidence of acute miliary disease of the internal organs. Course The prognosis is poor
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BCG Inoculation Specific lesions following BCG vaccination include the following: Lupus vulgaris may develop at or in the vicinity of the vaccination site after a latency period of several months or after I to 3 years.19,20 Individuals previously sensitive to tuberculin may exhibit a type of Koch's phenomenon. Necrosis and ulceration occur as in normal nonsensitive individuals but with a shorter time course. Regional adenitis is common, and general symptoms may be present. Local subcutaneous abscesses may form if the vaccination material has been injected too deeply into the skin, and excessive ulceration may ensue.* WWW.SMSO.NET
Severe regional adenitis is definitely the most common complication and occurs more often in the younger age groups. Scrofuloderma may develop, and suppuration may persist for 6 to 12 months. Generalized tuberculid-like eruptions have rarely been observed. Fatal disease due to generalized BCG tuberculosis is rare-1 per 10 million vaccinated-and occurs in immunologically compromised individuals. Generalized adenitis , osteitis, and tuberculous foci in distant organs (e.g., the joints) have occurred occasionally.The Tuberculids
Are symmetric generalized exanthems in the skin of tuberculous patients.originally,these exanthems were believed secondary to mycobacterial toxins,however,recent opinion and identification of mycobacterial DNA by PCR amplification reactions in affected tissue suggest that they are manifestation of hematogenous spread of bacilli in patients with tuberculin immunity.* WWW.SMSO.NET
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it is a lichenoid eruption of minute papules. in children and adolescents with tuberculosis. Incidence And Pathogenesis Uncommon Hematogenous spread of mycobacteria in an individual strongly sensitive to M. tuberculosis Associated with chronic tuberculous disease of the lymph nodes and bones or with specific pleurisy , it has been observed following BCG vaccination.
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Clinical ManifestationsAsymptomatic , confined to the trunk. The lesions consist of small, firm, follicular or parafollicular papules of a yellowish or pink color; they have a flat top or a minute horny spine or fine scales on their surface Lichenoid grouping is pronounced and results in the formation of rough, discoid plaques that tend to coalesce The lesions persist for months, but spontaneous involution eventually ensues Antituberculous therapy results in complete resolution within a matter of weeks.
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Differential DiagnosisLichen planus lichenoid secondary syphilis Papulonecrotic Tuberculid It is a symmetric eruption of necrotizing papules appearing in crops and healing with scar formation. Incidence common in the older dermatologic and pediatric literature but have become rare. It occurs preferentially in children or young adults
lichen nitidus Micropapular forms of sarcoidosis
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Pathogenesisbacteria cannot be demonstrated in lesions lupus vulgaris was seen to evolve from papulonecrotic tuberculids , and was cultured from some patients This suggests that mycobacteria may have been present in the papulonecrotic lesions but does not exclude the possibility that they may have lodged in these lesions secondarily Associated with tuberculous lymph nodes of internal organs. M. tuberculosis DNA has been detected in about 50 percent of patients.
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Clinical ManifestationsExtensor aspects of the extremities, buttocks, and lower trunk with a symmetric distribution Disseminated crops of dusky red, symptomless, pea-sized papules , with central depression and an adherent crust over a crater-like ulcer There is spontaneous involution, and pitted scars
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Pityriasis lichenoides et varioliformis acuta prurigo secondary syphilis
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Therapy of Skin TuberculosisChemotherapy First-line drugs are highly effective and are used mainly in the initial treatment of susceptible organisms : isoniazid, rifampin, aminoglycosides, and ethambutol Second-line drugs used mainly in the treatment of patients with drug-resistant mycobacteria : pyrazinamide, ethionamide, viomycin, kanamycin, capreomycin, and cycloserine
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Drug Combinations And RegimensThe aim of chemo-therapy for tuberculosis is to cure the disease as rapidly as possible. to prevent the emergence of resistant strains to prevent relapses intensive phase : Daily isoniazid, rifampin, pyrazinamide, and either ethambutol or streptomycin for 8 weeks continuation phase : aims at the elimination of remaining, "dormant"organisms: if they are susceptible to isoniazid and rifampin, these drugs are given either daily, three times weekly, or twice weekly for 16 weeks
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Special Considerations In The Therapy Of Tuberculosis Of The SkinA full antituberculous regimen is administered, even in localized forms of skin tuberculosis where a primary focus or evidence of an underlying organ tuberculosis or tuberculosis of lymph nodes exists. Tuberculosis verrucosa cutis and localized forms of lupus vulgaris without evidence of associated internal tuberculosis, isoniazid has been given alone with a high cure rate, for 12 months should be continued for at least 2 months after complete involution of the lesions
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If there is concomitant internal tuberculosis or if drug resistance emerges, combination therapy is mandatory also in localized lupus vulgaris. Surgical intervention : scrofuloderma , small lesions of lupus vulgaris , tuberculosis verrucosa cutis* WWW.SMSO.NET
IsoniazidIt penetrates into all body fluids and cells and also into sclerotic tissue so that it is effective even in old fibrotic lesions daily dose of the drug is 5 mg/kg with a maximum of 300 mg side effects : fever , skin eruptions , peripheral neuritis , hepatotoxicity, and hematologic complications (agranulocytosis, eosinophilia, anemia, and thrombocytopenia) Pyridoxine should be given concomitantly to prevent peripheral neuropathy
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Pyrazinamide
should be given in a dose of 15 to 30 mg/kg with a maximum of 2 g daily Ethambutol bacteriostatic drug given in doses of 15 to 25 mg/kg used in combination with other drugs, usually rifampin and isoniazid It accumulates in patients with impaired renal function and should not be given to children under 13 years of age
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RifampinIt should not be used alone as mycobacteria rapidly develop resistance single oral dose of 600 mg/day patients should be warned that the drug may impart an orange stain to excretions, including saliva Streptomycin it is bactericidal for M. tuberculosis in vitro but its activity in vivo is essentially suppressive it does not penetrate cell membranes , (and thus cannot kill intracellular organisms).