Quiz 33: What is your diagnosis?

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Diagnosis: Quiz 33

Quiz 33

Answer:  Dermatophytosis

Criteria for diagnosis clinically: A cluster of rust-colored papules, one of them curvilinear, covered by scale is representative of dermatophytosis.

Differential diagnosis clinically: This could be another infectious process, such as one caused by an atypical mycobacterium or a deep fungus. Scraping of the surface of a lesion should provide scales that house fungi demonstrable by KOH. Biopsy also permits the organisms causative to be revealed, as is evident here in this section stained conventionally by H&E.

Criteria for diagnosis histopathologically: Septate hyphae and spores in cornified cells of surface and infundibular epidermis are diagnostic of dermatophytosis, the fungi in the infundibular canal being associated with compact orthokeratosis, as well as with a collection of neutrophils. Those changes are accompanied by a "bottom heavy" perivascular infiltrate made up largely of lymphocytes joined by an occasional plasma cell.

Differential diagnosis histopathologically: There is none.

Clinicopathologic correlation: The papules are formed mostly of infiltrates of inflammatory cells, both around vessels in the dermis and within an infundibulum; the rust color resulted from venules in the upper part of the dermis being dilated widely and filled with erythrocytes; and the scale consists of compact orthokeratosis that, in loci, alternates with corneocytes arranged in fashion basket-woven.

Options for therapy predicated on knowledge of histopathologic finding: Topical application of a fungicide should be effective against hyphae present in surface and infundibular epidermis. Alternatively, an antifungal administered systemically will be curative.

1) Clinically, the papules arrayed in a cluster qualify as those of Majocchi's granuloma, i.e., a suppurative infundibulitis induced by a dermatophyte. The term, like so many in dermatology and dermatopathology, is misleading. Lesions of Majocchi's granuloma, especially ones early in the course chronological of them, are not granulomatous, as is evident here.

2) So-called Majocchi's granuloma fundamentally is a suppurative infundibulitis that, in time, is marked by rupture of infundibula with consequent suppurative, suppurative granulomatous, granulomatous, and fibrosing inflammation in the dermis.

3) Although the dermatophytes are identifiable easily in sections stained by hematoxylin and eosin, they are made even more apparent by staining with the periodic acid-Schiff (PAS) reagent.

4) A clue to the presence of dermatophytosis is the "sandwich sign," namely, two "slices" of cornified cells, the upper being organized in pattern basket-woven and the lower being arranged compactly, the hyphae lodged in between the two.

5) A cornified layer predominantly parakeratotic or one that houses serum, particularly in abundance, will not be hospitable to fungi, the former situation being hostile because it signifies an increase in epidermopoiesis, with desquamation of those nucleus-containing corneocytes being inevitable, and death of the fungi. The latter circumstance is murderous because it is bacteriocidal. The best places to detect hyphae of dermatophytoses is orthokeratotic corneoyctes, especially in those arranged compactly, in the zone between a basket-woven "slice" and a compactly-arranged "slice" of corneocytes in the stratum corneum, and in corneocytes very nearby collections of neutrophils.

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