Galli-Galli Disease: A Rare Acantholytic Variant of Dowling-Degos Disease

Galli-Galli disease is a rare acantholytic variant of Dowling-Degos disease, with few cases reported in the literature. We describe a case of Galli-Galli disease and review the literature.


Introduction
Galli-Galli disease (GGD) is a very rare variant of the Dowling-Degos disease (DDD) with the histologic finding of focal acantholysis. It was originally reported by Bardach et al. in 1982, who described the disease in two brothers and named it eponymically after this family [1].

Case Report
A previously healthy 67-year-old Caucasian woman presented with a 15-year history of widespread skin lesions. She had recurrent pruritic papular eruptions and slowly progressing brownish lentigo-like macules. The skin lesions began on the trunk and then became generalized, involving the extensor and flexural surfaces of extremities, including the back of the hands, neck, and trunk. Clinical examination revealed numerous generalized symmetrically distributed brownish macules and some pruritic, hyperkeratotic, erythematous papules (Figure 1). The face, palms, and soles were spared, and she had no nail, hair, teeth, or mucosal alterations. There was no atrophic or hypopigmented lesions. No family history of similar lesions was known. She was previously treated with topical corticosteroids without improvement. Laboratory examinations demonstrated no abnormalities. Histopathologic examination of three biopsy specimens revealed digitiform epithelial downgrowths of the rete ridges, with hyperpigmentation of the basal layer confined to the tips of the rete ridges. Multiple foci of suprabasilar acantholysis were also observed ( Figure 2) and a mixed dermal inflammatory infiltrate. In one of the biopsy specimens, we found acantholytic and dyskeratotic cells (Figure 2(b)). Direct immunofluorescence was negative.
Taken together, clinical and pathological data suggested a diagnosis of Galli-Galli disease. Treatment was very difficult with only short-term partial improvement using acitretin (25 mg/day) and topical corticosteroids.
A few patients have been described in the literature. A literature search revealed 9 previous case reports of GGD, with a total of 17 patients (Table 1). According to the reported cases, the age range of presentation is 15 to 67 years, 11 patients were male, and 6 were female. All the patients  in the reports had reticulated hyperpigmentation in the flexural areas, with the exception of one. In our patient, the characteristic hyperpigmentation of the axillae and inguinal region could not be detected, rendering a diagnosis of GGD difficult.
In 15 of the 17 cases a skin biopsy was performed, and in all of this cases acantholysis was identified, but dyskeratosis was present in only 3 cases. In our case we also identified dyskeratotic cells in one of the fragments, closely resembling features of Darier's or Grover's diseases. However, Darier's disease could be ruled out by the presence of areas of digitate proliferations of the rete ridges, clinically it starts early, lentigo-like macules are rare, and it is commonly associated with nail and mucous membrane involvement that was absent in our patient. In Grover's disease involvement of the distal extremities, as in our patient, and the presence of brown lentigo-like macules are not common. Histologically, areas of lentiginous elongations of the rete ridges are not observed in Grover's disease.
Because of the overlap of clinical features, to the majority of authors GGD is best considered as an acantholytic variant of Dowling-Degos disease rather than an entity of its own [2,3]; however, some authors defend that if one accepts the histopathological finding of acantholysis as a pathognomonic feature, GGD should be classified as its own disease entity [8].