borderline tuberculoid leprosy

Borderline tuberculoid leprosy is a cutaneous condition similar to tuberculoid leprosy except the skin lesions are smaller and more numerous.

Lesions in this form are similar to those in the tuberculoid form, but they are smaller and more numerous. The nerves are less enlarged and alopecia is less in borderline tuberculoid leprosy than in other forms.

Disease can remain in this stage, it can convert back to the tuberculoid form, or it can progress to lepromatous leprosy.

Clinical synopsis

 erythematous plaques

Pathology

In the borderline tuberculoid form, well-developed epithelioid cell granulomas are apparent and diffuse, but few or no Langhans giant cells are observed.

Few lymphocytes are present in the epidermis in this form, compared with tuberculoid leprosy.

Bacilli are absent or rare, but they can be found in dermal nerves and in the arrector pilorum. Nerves are moderately swollen.

 mixed lymphocytic and granulomatous inflammatory infiltrate in perivascular and perineural distribution.
 Granulomas poorly formed and containing "foamy cells" with clear bubbly cytoplasms.
 possible perineural distribution of the inflammatory changes
 the infiltrate can involve errector pilar muscle (Mycobacterial lepra have predilection to pilar muscle.)

 Fite and AFB stains can fail to reveal microorganisms.

The diagnosis of leprosy could not be made on purely histological grounds.

Case reports

 Dermpedia

Links

 eMedicine:1104977

See also

 leprosy

• borderline leprosy
• tuberculoid leprosy