Leprosy

Am J Dermatopathol. 2008 Dec;30(6):555-560. Abstract quote

Lucio's phenomenon (LPh) is a vasculitis clinically described in 1852 and microscopically documented in 1948 in patients with diffuse lepromatous leprosy; however, at present, there is no a clear concept about the pathogenesis of the necrosis, or about the type, size, and site of the damaged vessel.

The objective of this study was to elucidate the type, size, site, and form of vessel damage in LPh in a retrospective, clinical, and histopathological study. Clinical information was obtained from the charts and records and/or from the histopathology request. Slides stained with hematoxylin and eosin, Ziehl-Neelsen, and Fite-Faraco were retrieved from our files. Direct immunofluorescence had been performed in 6 cases. Twelve cases fulfilled clinical evidence to make unequivocal diagnosis of diffuse lepromatous leprosy with LPh. All of them had necrotic, irregular, purpuric, and/or ulcerative lesions, which under the microscope showed medium-sized arteries, with their walls involved by clusters of macrophages containing large amounts of bacilli, distortion of the structure of the vessel wall, narrowing, and obliteration of their lumen. Smaller vessels showed changes of the leukocytoclastic type.

LPh is a distinctive type of granulomatous and necrotizing panvasculitis; the involved vessels are mostly medium-sized arteries, located deeply in the skin, at the base, and within the hypodermis, but any other vessel is likewise involved, their occlusion leads to ischemic necrosis of the whole skin, frequently with detachment of the epidermis. These changes explain clearly and logically the clinical features observed more than 150 years ago.

Epidemiology
Pathogenesis
Gross Appearance and Clinical Variants
Histopathological Features and Variants
Special Stains/ Immunohistochemistry/ Electron Microscopy
Differential Diagnosis
Commonly Used Terms
Internet Links

EPIDEMIOLOGY	CHARACTERIZATION
SYNONYMS	Hansen's disease
GEOGRAPHY	Endemic to tropical and subtropical regions

PATHOGENESIS	CHARACTERIZATION
Mycobacterium leprae	Cannot be cultured on artifical media May be inoculated into armadillos which have a lower ambient body temperature

HISTOLOGICAL TYPES	CHARACTERIZATION
General
Indeterminate	Superficial and deep perivascular and periadnexal lymphohistiocytic infiltrate which may occasionally destroy adnexa and nerves Fite stain usually negative
Tuberculoid	Well formed granulomas around adnexa and nerves and occasionally subcutaneous tissue Occasional giant cells Fite stain with few bacilli
Borderline	Less conspicuous granulomas with increased bacilli by Fite stain Lymphocytes usually lacking
Lepromatous	Nodular to diffuse infiltrates composed of lymphocytes forming small nodules mixed with numerous lipid laden macrophagesss Bluish gray granular cytoplasm Fite stain positive for numerous organisms
LUCIO'S PHENOMENON
Lucio's Phenomenon Is a Necrotizing Panvasculitis: Mostly a Medium-Sized Granulomatous Arteritis. Magaña M, Fernández-Díez J, Magaña ML. From the *Centro Médico Nacional Siglo XXI, I.M.S.S.; daggerCentre for Dermatology & Dermatopathology; and double daggerService of Dermatology, Hospital General de México and School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico City, Mexico.	Am J Dermatopathol. 2008 Dec;30(6):555-560. Abstract quote Lucio's phenomenon (LPh) is a vasculitis clinically described in 1852 and microscopically documented in 1948 in patients with diffuse lepromatous leprosy; however, at present, there is no a clear concept about the pathogenesis of the necrosis, or about the type, size, and site of the damaged vessel. The objective of this study was to elucidate the type, size, site, and form of vessel damage in LPh in a retrospective, clinical, and histopathological study. Clinical information was obtained from the charts and records and/or from the histopathology request. Slides stained with hematoxylin and eosin, Ziehl-Neelsen, and Fite-Faraco were retrieved from our files. Direct immunofluorescence had been performed in 6 cases. Twelve cases fulfilled clinical evidence to make unequivocal diagnosis of diffuse lepromatous leprosy with LPh. All of them had necrotic, irregular, purpuric, and/or ulcerative lesions, which under the microscope showed medium-sized arteries, with their walls involved by clusters of macrophages containing large amounts of bacilli, distortion of the structure of the vessel wall, narrowing, and obliteration of their lumen. Smaller vessels showed changes of the leukocytoclastic type. LPh is a distinctive type of granulomatous and necrotizing panvasculitis; the involved vessels are mostly medium-sized arteries, located deeply in the skin, at the base, and within the hypodermis, but any other vessel is likewise involved, their occlusion leads to ischemic necrosis of the whole skin, frequently with detachment of the epidermis. These changes explain clearly and logically the clinical features observed more than 150 years ago.

SPECIAL STAINS/ IMMUNOPEROXIDASE	CHARACTERIZATION
SPECIAL STAINS	Fite-Franco stain (modified Acid Fast stain) is most sensitive special stain
IMMUNOPEROXIDASE	Specific antibodies against phenolic glycolipid-I of M. leprae
S100
S-100 as a useful auxiliary diagnostic aid in tuberculoid leprosy. Gupta SK, Nigam S, Mandal AK, Kumar V. Department of Pathology, Maulana Azad Medical College, New Delhi, India.	J Cutan Pathol. 2006 Jul;33(7):482-6 Abstract quote BACKGROUND: The diagnosis of tuberculoid leprosy is often difficult on hematoxylin and eosin (H&E) due to the absence of demonstrable nerve destruction. This study evaluates the utility of S-100 staining in identifying nerve fragmentation and differentiation of tuberculoid leprosy from other cutaneous granulomatous diseases. METHODS: Fifty cases of leprosy including 38 borderline tuberculoid (BT), two tuberculoid (TT), and 10 indeterminate leprosy (IL) were studied. Eleven controls of non-lepromatous cutaneous granulomatous lesions were included. S-100 was used for identifying the following dermal nerve patterns: infiltrated (A), fragmented (B), absent (C), and intact (D) nerves. RESULTS: On H&E, only 18/38 (47.4%) BT cases and 1/2 (50%) TT cases revealed neural inflammation. On S-100 staining of BT cases, 28/38 (73.7%) showed pattern B followed by patterns C and A in 8/38 (21.1%) and 2/38 (5.3%) cases, respectively. Both the TT cases showed pattern B. Only intact nerves (D) were seen in all the control cases. S-100 identified nerve damage in 4/10 (40%) IL cases. The patterns A, B, and C had sensitivity, specificity, and positive and negative predictive values of 100% in diagnosing tuberculoid (BT + TT) leprosy. CONCLUSIONS: S-100 is superior to H&E in identifying nerve fragmentation (p < 0.01). It also aids the differential diagnosis of tuberculoid leprosy.
FLUORESCENT MICROSCOPY
Role of fluorescent microscopy in detecting Mycobacterium leprae in tissue sections. Nayak SV, Shivarudrappa AS, Mukkamil AS. Department of Pathology, Victoria Hospital, Fort, Bangalore, India.	Ann Diagn Pathol 2003 Apr;7(2):78-81 Abstract quote We compared the sensitivity of the fluorescent method with that of he modified Fite-Faraco method in the detection of Mycobacterium leprae in tissue sections. Fifty-six skin biopsies were obtained from patients having leprosy, particularly the paucibacillary type. Minor alterations were made in the deparaffinization and staining technique, as compared with Kuper and May's method, to obtain optimum fluorescence. Of 56 biopsies studied, 39 showed organisms by the fluorescent method and only 25 showed organisms by the modified Fite-Faraco method. The fluorescent method was found to be more advantageous than the modified Fite-Faraco method, particularly in paucibacillary cases. Fluorescent microscopy has the advantage of speed and ease of screening and reduces observer fatigue. Bacillary positivity rates were higher in the fluorescent method than in the modified Fite-Faraco method in each type of leprosy.