Quiz 38: What is your diagnosis?

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Diagnosis: Quiz 38

Quiz 38

Answer: Grover's disease

Criteria for diagnosis histopathologically: In addition to a superficial perivascular infiltrate of lymphocytes, foci of suprabasal clefts, above which reside acantholytic spinous, granular, and parakeratotic cells, are findings in keeping with Grover's disease.

Differential diagnosis histopathologically: This cannot be Darier's disease because above every column of parakeratosis is a stratum corneum typified by a normal basket-woven pattern, an indication that the lesion is of relatively recent onset, probably less than two weeks old, which is not the case in a biopsy specimen harvested from a lesion of Darier's disease. The changes pathologic in the latter malady are not surmounted by a normal cornified layer because they are of months' or years' duration. The same is true for a lesion of the systematized epidermal nevus which goes by the incorrect designation of "linear Darier's disease" (often the configuration is not linear and never is it an authentic manifestation of Darier's disease). The keratotic papules that constitute it, like those of Darier's disease, are long-standing and, that being so, a normal basket-woven cornified layer does not cover each of the columns of parakeratosis. What has just been written for Darier's disease and for a systematized epidermal nevus applies also to acantholytic dyskeratotic acanthoma, a keratotic papule that usually presents itself as a solitary lesion and at the time of biopsy is of many weeks', months', or even years' duration. That longevity precludes the possibility of a basket-woven cornified layer sitting atop each of the columns of parakeratosis. In contrast, in Grover's disease, the lesion at the time of biopsy may be only a few days old and, for that reason in that circumstance, columns of parakeratosis, when present, are covered often by an umbrella of orthokeratotic corneocytes arrayed in a manner basket-woven, as is expected in a normal stratum corneum. This is not Galli-Galli disease (reputed to be that variant of Dowling-Degos disease punctuated by foci of acantholytic dyskeratosis) because the cords of pigmented keratocytes issue dramatically from surface epidermis but only negligibly from infundibular epidermis.

Criteria for diagnosis clinically: Because a drug eruption cannot be excluded, biopsy is essential if a diagnosis of Grover's disease is to be established.

Clinicopathologic correlation: The surface of this particular papule is smooth because the columns of parakeratosis are obscured from view clinical by a normal basket-woven cornified layer; the papule itself is formed by changes in the epidermis, namely, foci of acantholytic dyskeratosis and cords of keratocytes that extend well into the papillary dermis, as well as alterations in the upper part of the dermis, to wit, infiltrates of lymphocytes; and the pink hue is the result of erythrocytes, in vivo, having filled widely dilated venules of the superficial plexus.

Options for therapy predicated on knowledge of histopathologic findings: Because Grover's disease is characterized by disordered cornification, dyskeratotic cells often being joined by parakeratosis, it is not surprising that a retinoid delivered systemically is helpful in bringing the process to a halt. Grover's disease is notoriously refractory to treatment by other agents administered systemically or applied topically.

1) Because the changes of focal acantholytic dyskeratosis in this section of tissue are accompanied by cords of markedly melanized epidermal keratocytes that protrude into a widened papillary dermis, the findings  in toto  pictured in these photomicrographs could be misconstrued as those of Galli-Galli disease, that entity supposedly being Dowling-Degos disease interrupted by foci of acantholytic dyskeratosis. In fact, the very same patient that forms the basis of this Interactive Quiz was reported on in the Journal of the American Academy of Dermatology  [2007;56:S86-91] as an example of Galli-Galli disease. The pigmented cords of keratocytes certainly are reminiscent of those in Dowling-Degos disease and the findings histopathologic in toto  are consonant with what is claimed to be Galli-Galli disease.

2) Galli-Galli disease is purported to be nothing other than an acantholytic dyskeratotic variant of Dowling-Degos disease. If that truly were so, then the findings depicted in these photomicrographs could, conceivably, be those of Galli-Galli disease, yet this patient, as is evident clinically, does not have Dowling-Degos disease, but Grover's disease.

3) In our judgment, many of the patients reported on as having Galli-Galli disease really have Grover's disease. How, then, do we explain the pigmented cords of epidermal keratocytes present in this section of tissue, they resembling those indispensible to diagnosis histopathologic of Dowling-Degos disease (in the photomicrographs shown here, the cords seem to have created a reticulate pattern by virtue of the section being oriented obliquely)?

Our hypothesis is as follows: Because for more than 30 years it has been established that there are at least five variants histopathologic of Grover's disease, each of them typified by foci of acantholytic dyskeratosis, namely, the Darier, the Hailey-Hailey, the pemphigus vulgaris, the pemphigus foliaceus, and the spongiotic-acantholytic, there could be still other patterns of it identifiable by microscopy conventional, for example, a Dowling-Degos type. We believe that the changes histopathologic illustrated here represent the Dowling-Degos type of Grover's disease. It must be stressed that the patterns of epithelium in Grover's disease referred to by us as Darier, Hailey-Hailey, Dowling-Degos, etc., actually are Darier-like, Hailey-Hailey-like, Dowling-Degos-like, etc. In short, the changes histopathologic resemble those of Darier's disease, Hailey-Hailey disease, Dowling-Degos disease, etc; they are not representative, in fact, of those diseases.

4) How does one account for those patients with so-called Galli-Galli disease who seem to have authentic Dowling-Degos disease both on grounds clinical and histopathologic? Focal acantholytic dyskeratosis is a repeatable pattern of epithelium in skin, analogous to epidermolytic hyperkeratosis, cornoid lamellation, pale-cell acanthosis, and epithelial (follicular) mucinosis, and it is the  sine qua non  for diagnosis of a number of diseases, ranging from inflammatory (e.g., Grover's) to hamartomatous (e.g., a systematized nevus). It, like the epithelial analogues, also can appear as a change incidental to dominant findings of a process pathologic recognizable with facility (e.g., in the vicinity immediate of a melanocytic nevus that affects the dermoepidermal junction or of a primary cutaneous melanoma). That being the case, it should come as no surprise that some patients with Dowling-Degos disease could display, in sections of tissue typical of that condition, incidental foci of acantholytic dyskeratosis. That coincidence, however, does not qualify the process as one special and different, i.e., Galli-Galli disease, but rather it simply represents Dowling-Degos disease with one or more incidental foci of acantholytic dyskeratosis. In appearance clinical and histopathologic, Dowling-Degos disease

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