Which histologic findings suggest miliaria?

Updated: Mar 27, 2020
  • Author: Nikki A Levin, MD, PhD; Chief Editor: Dirk M Elston, MD  more...
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In miliaria crystallina, intracorneal or subcorneal vesicles communicate with eccrine sweat ducts, without surrounding inflammatory cells. Obstruction of the eccrine duct may be observed in the stratum corneum.

In miliaria rubra, spongiosis and spongiotic vesicles are observed in the stratum malpighian, in association with eccrine sweat ducts. Periductal inflammation is present.

In early lesions in miliaria profunda, a predominantly lymphocytic periductal infiltrate is present in the papillary dermis and lower epidermis. A PAS-positive diastase-resistant eosinophilic cast may be seen in the ductal lumen. In later lesions, inflammatory cells may be present lower in the dermis, and lymphocytes may enter the eccrine duct. Spongiosis of the surrounding epidermis and parakeratotic hyperkeratosis of the acrosyringium may be observed.

In the granulomatous giant centrifugal variant of miliaria profunda, biopsies show mild spongiosis and acanthosis, hypergranulosis, and hyperplasia of the acrosyringia, the eccrine ducts, and infundibula, with invagination by keratin plugs. There is a granulomatous inflammatory infiltrate within the dermis, consisting of lymphocytes and foreign body giant cells with a few neutrophils centered around the ruptured straight portion of the eccrine duct. [27]

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