Background: The evaluation of patients with cicatricial alopecia is particu
larly challenging, and dermatopathologists receive little training in the i
nterpretation of scalp biopsy specimens. Accurate interpretation of specime
ns from patients with hair disease requires both qualitative (morphology of
follicles, inflammation, fibrosis, etc.) and quantitative (size, number, f
ollicular phase) information. Much of this data can only be obtained from t
ransverse sections. In most cases, good clinical/pathologic correlation is
required, and so clinicians should be expected to provide demographic infor
mation as well as a brief description of the pattern of hair loss and a cli
nical differential diagnosis.
Results: The criteria used to classify the various forms of cicatricial alo
pecia are relatively imprecise, and so classification is controversial and
in a state of evolution. There are five fairly distinctive forms of cicatri
cial alopecia: 1) chronic, cutaneous lupus erythematosus discoid LE); 2) li
chen planopilaris; 3) dissecting cellulitis (perifolliculitis abscedens et
suffodiens); 4) acne keloidalis; and 5) central, centrifugal scarring alope
cia (follicular degeneration syndrome, folliculitis decalvans, pseudopelade
). Not all patients with cicatricial alopecia can be confidently assigned t
o one of these five entities, and "cicatricial alopecia, unclassified" woul
d be an appropriate label for such cases.
Conclusion: The histologic features of five forms of cicatricial alopecia a
re reviewed. Dermatopathologists can utilize a "checklist" to catalog the d
iagnostic features of scalp biopsy specimens. In many, but not all, cases t
he information thus acquired will "match" the clinical and histologic chara
cteristics of a form of cicatricial alopecia. However, because of histologi
c and clinical overlap between the forms of cicatricial alopecia, a definit
ive diagnosis cannot always be rendered.