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Background

Leprosy is a disease which has been associated with tremendous social stigma with cases recorded in the Old Testament. It is an infectious disease caused by Mycobacterium leprae. The organism grows in a cooler temperature than most bacteria and thus collects in cooler parts of the body such as the extremities and peripheral nerves. This disease presents with a variety of appearances based upon the immune status of the patient.

OUTLINE

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

 

GROSS APPEARANCE/
CLINICAL VARIANTS
CHARACTERIZATION
General Clinical presentation is dependent upon the immune status of the patient
Indeterminate
Few hypopigmented scaly macules on face and limbs resembling tinea versicolor
Tuberculoid
Solitary or multiple
Well demarcate hypesthetic or anesthetic plaques distributed asymetricaly
Cutaneous nerves may be enlarge
Borderline
Poorly circumscribed macules and papules with raised centers
Lepromatous
Symmetrically distributed nodules with irregular borders
VARIANTS  
NO LESIONS  
Microscopic leprosy skin lesions in primary neuritic leprosy.

Menicucci LA, Miranda A, Antunes SL, Jardim MR, da Costa Nery JA, Sales AM, Sarno EN.

Leprosy Laboratory, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro, Brazil.
J Am Acad Dermatol. 2005 Apr;52(4):648-52. Abstract quote  

The histologic diagnosis of primary neuritic leprosy (PNL) remains a public health care concern, especially when nerve biopsies cannot be performed. As such, some authors emphasize the importance of performing a skin biopsy of a hypoesthetic area even without clinically visible lesions.

In this study, an attempt was made to define the histologic changes in the sensory altered skin of 42 clinically diagnosed PNL patients. Histologic alterations caused by leprosy were seen in 31% of these patients: 6 were classified as borderline tuberculoid and 7 as indeterminate. In addition, 33% showed mild, non-specific, mononuclear cell infiltrates around the blood vessels within the papillary and reticular dermis that probably reflected an early inflammatory reaction to Mycobacterium leprae infection. Only 36% of those biopsied had no significant lesions.

Our results suggested that, while not all PNL patients are similar, histologic skin examination can contribute to early leprosy detection and commencement of adequate treatment.

 

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.

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.

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.


DIFFERENTIAL DIAGNOSIS CHARACTERIZATION
MYCOBACTERIUM AVIUM INTRACELLULARE INFECTION  
Cutaneous Mycobacterium avium intracellulare infection in an HIV+ patient mimicking histoid leprosy.

Boyd AS, Robbins J.

Department of Medicine (Dermatology), Vanderbilt University, Nashville, Tennessee, USA.
Am J Dermatopathol. 2005 Feb;27(1):39-41. Abstract quote  

Cutaneous infections with Mycobacterium avium intracellulare (MAI) are uncommon in healthy patients but may arise in those with underlying immunocompromise, including patients with HIV. Their clinical manifestations are protean.

We report an AIDS patient with a cutaneous MAI infection that clinically and histopathologically mimicked histoid leprosy, a presentation not previously described in this population.

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Rosai J. Ackerman's Surgical Pathology. Ninth Edition. Mosby 2004.
Sternberg S. Diagnostic Surgical Pathology. Fourth Edition. Lipincott Williams and Wilkins 2004.
Robbins Pathologic Basis of Disease. Seventh Edition. WB Saunders 2005.
DeMay RM. The Art and Science of Cytopathology. Volume 1 and 2. ASCP Press. 1996.
Weedon D. Weedon's Skin Pathology Second Edition. Churchill Livingstone. 2002
Fitzpatrick's Dermatology in General Medicine. 6th Edition. McGraw-Hill. 2003.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fifth Edition. Mosby Elesevier 2008


Commonly Used Terms

Basic Principles of Disease
Learn the basic disease classifications of cancers, infections, and inflammation

Commonly Used Terms
This is a glossary of terms often found in a pathology report.

Diagnostic Process
Learn how a pathologist makes a diagnosis using a microscope

Surgical Pathology Report
Examine an actual biopsy report to understand what each section means

Special Stains
Understand the tools the pathologist utilizes to aid in the diagnosis

How Accurate is My Report?
Pathologists actively oversee every area of the laboratory to ensure your report is accurate

Got Path?
Recent teaching cases and lectures presented in conferences


Internet Links

Last Updated December 1, 2008

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