Brocq Pseudopelade Workup

Updated: Feb 28, 2022
  • Author: Kendall M Egan, MD, FAAD; Chief Editor: William D James, MD  more...
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Workup

Procedures

Scalp biopsy

Two 4-mm punch biopsy specimens should be obtained from an orientation along the direction of the hair follicle. Specimens should ideally be taken from a clinically well-established but active area of alopecia and inflammation to include both normal and affected hair-bearing areas. Trichoscopy may be useful for biopsy site selection. [19] One punch biopsy specimen should be submitted for horizontal sectioning and one for vertical sections if possible, both stained with hematoxylin and eosin and elastic tissue stains. The second punch biopsy specimen can be bisected vertically to accommodate both direct immunofluorescence (DIF) and hematoxylin and eosin staining. [10]

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Histologic Findings

The histopathologic criteria established by Pinkus were not correlated in any way with the clinical features. [20] Thus, pseudopelade as described by Pinkus is a histologic and not a clinical entity. In secondary pseudopelade, the histologic findings are those of a burnt-out scarring alopecia with absent hair follicles and fibrosis. Elastic tissue is absent in scarred areas. Idiopathic pseudopelade is characterized by a contracted dermis with dense collagen and loss of space between collagen bundles. Elastic fibers are recoiled and appear thick. Broad fibrous tract remnants are noted with preservation of the elastic sheath.

Cummins et al correlate the following histopathologic features of pseudopelade of Brocq with the clinical features of scarred, skin-colored plaques with erythema and slight follicular hyperkeratosis:

  • Decreased amount of sebaceous glands and terminal hairs

  • Follicular stellae without overlying follicle

  • Mild inflammation of the dermis

  • Cylindrical columns of connective tissue at previous follicle sites​ [19]

Agarwal et al note that IgM positivity in direct immunofluorescence is significant in differentiating lichen planus from pseudopelade of Brocq. [21]

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