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Secondary scarring alopecias from infections
The first, as well as the most dominant, cause of secondary scarring
alopecia is infection and it may be of different types including
infections resulting from bacterial, fungal and viral attacks.
Bacterial Infection
As in some primary scarring alopecia conditions, tissue homogenate
cultures (composed of similar or identical tissues) of bacterial
folliculitis (inflammation of a hair follicle or follicles) often
bear testimony to the role played by Staphylococcus aureus in this
kind of cicatricial alopecia. Folliculitis cultures, at times, also
reveal the presence of Corynebacterium acnes. Folliculitis can be
part of the larger issue of bacterial infection.
Bacterial folliculitis manifests itself as superficial follicular
papules, pustules (a vesicle or an elevation of the cuticle with
an inflamed base, containing pus), or as some kind of inflammatory
eruption from deep in the skin. As far as histological features
of the bacteria infested condition is concerned, the initial stage
shows a kind of suppurative (pus forming) infundibular (the upper
part of the hair follicle) folliculitis. Later on, the suppurative
infundibular folliculitis festers or aggravates into a severe pus
containing folliculitis (furuncle or boil) with perifollicular (surrounding
a hair follicle, usually used to describe the histopathologic appearance
of the infiltrate surrounding a hair follicle) fibrosis (the formation
of fibrous tissue). With the condition worsening – due to
follicular destruction and extensive fibrosis of the fibrous tract
as also of the interstitial (situated between parts or in the interspaces
of a tissue) dermis – cicatricial alopecia sets in.
Fungal Infection: A secondary scarring alopecia condition like
Tinea capitis shows evidence of the presence of fungal hyphae (the
fine, branching tubes which make up the body of a multicellular
fungus) in and around the hair shafts but not in overlying epidermis
when a scalp-skin sample is viewed under microscope. Tissue cultures
also help in the proper diagnosis.
This type of alopecia is characterized by hair loss in all its
stages of development. The early stage is characterized by a non-inflammatory
alopecia and it develops fine scaling, pustular (pus bearing) folliculitis,
seborrhea (a morbidly increased discharge of sebaceous matter upon
the skin)-like dermatitis or kerion (a granulomatous secondarily
infected lesion complicating fungal infection of the hair; typically,
a raised boggy lesion) as the condition deteriorates.
Not all of these presentations, however, show scarring; only the
ones with deep inflammation lead to permanent scarring and follicle
loss. Initially the inflammation is neutrophilic (pertaining to
or characterized by neutrophils, such as an exudate in which the
predominant cells are neutrophilic granulocytes) but gradually changes
to mixed and granulomatous traits (chronic inflammatory lesion characterized
by large numbers of cells of various types – macrophages,
lymphocytes, fibroblasts, giant cells – some degrading and
some repairing the tissues).
Viral Infection:
Herpes zoster, a form of herpes (an acute inflammatory disease)
that infects sensory nerves, causing pain and eruptions, also affects
the scalp and can lead to a cicatricial alopecia condition. This
condition is marked by the presence of painful grouped vesicles
(a closed membrane shell around fluid), ulcers, crusts, or erythematous
(unusually reddened) plaques in a dermatomal (dermatome means the
area of skin innervated by a single posterior spinal or sensory
nerve) distribution.
The histologic changes are inclusive of chronic lymphocytic destructive
folliculitis with intra-nuclear viral presence. Viral culture and
Tzanck tests help in the proper detection of the condition. As far
as remedial measures are concerned, treatment with antiviral agents
is known to terminate the process of follicular destruction and
avert herpes zoster induced cicatricial alopecia.
Secondary
scarring alopecias from dermatoses
Dermatoses, i.e., skin inflammation, especially from two conditions – psoriasis
(a common chronic, squamous dermatosis, marked by exacerbations
and remissions and having a polygenic inheritance pattern) and pityriasis
amiantacea (an inflammatory condition of the scalp in which heavy
scales extend onto the hairs and bind the hair fibers together) – can
lead to cicatricial alopecia.
What happens in the case of psoriasis of the scalp is that the
outbreak of severe inflammation, pustules and persistent scalp plaques
in the skin of affected people initiates scarring alopecia in hair
follicles of affected skin. In the case of pityriasis amiantacea,
the scalp (rather the base of the hair shafts) is covered with mica-like
adherent scales. Any attempt at physically removing the scales uproots
the hair strands as well. This is effectively a type of traction
alopecia. If hair is repeatedly plucked then the hair follicles
accumulate damage and disruption. This can promote inflammation
around the follicles and the combined result may be scarring alopecia.
The histological presentations of both the disorders exhibit spongiotic
infundibular lymphocytic folliculitis and perifolliculitis (the
presence of an inflammatory infiltrate surrounding hair follicles;
frequently occurs in conjunction with folliculitis). These changes
in tissue structures bring about changes in the follicle growth
cycle and lead to severe consequences like telogen effluvium and
eventual miniaturization of the follicles. With further aggravation,
the follicular epithelium is destroyed and becomes bereft of sebaceous,
oil secreting glands. Eventually, the condition can provoke a granulomatous
reaction and permanent hair loss occurs.
The outbreak of such papulosquamous (denoting an eruption composed
of both papules and scales) scalp disorders can be contained by
the use of anti-bacterial, anti-fungal, keratolytic (promoting shedding
of the epidermis), anti-inflammatory and anti-proliferative agents.
As in many cases of scarring alopecia, topical corticosteroid preparations
remain a mainstay of treatment.
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