Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2025;15(4):4640 1 Dermoscopic Features and Diagnostic Criteria of Galli-Galli Disease: A Clinical Update Simonetta Piana1, Enrico Zendri2 1 Pathology Unit, Azienda USL-IRCCS di Reggio Emilia, Reggio Emilia, Italy 2 Dermatology Unit, Ospedale Civile di Guastalla, Azienda USL-IRCCS di Reggio Emilia, Reggio Emilia, Italy Key words: Galli-Galli disease, reticulate pigmentary disorders, pigmentary skin disordes, dermoscopy Citation: Piana S, Zendri E. Dermoscopic Features and Diagnostic Criteria of Galli-Galli Disease: A Clinical Update. Dermatol Pract Concept. 2025;15(4):4640. DOI: https://doi.org/10.5826/dpc.1504a4640 Accepted: September 26, 2024; Published: October 2025 Copyright: ©2025 Piana et al. This is an open-access article distributed under the terms of the Creative Commons Attribution- NonCommercial License (BY-NC-4.0), https://creativecommons.org/licenses/by-nc/4.0/, which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original authors and source are credited. Funding: None. Competing Interests: None. Authorship: All authors have contributed significantly to this publication. Corresponding Author: Simonetta Piana, Pathology Unit, Azienda USL-IRCCS di Reggio Emilia Viale Risorgimento, 80, Reggio Emilia, Italy. ORCID 0000-0003-4875-6977. E-mail address: Simonetta.Piana@ausl.re.it Introduction Galli-Galli disease (GGD) is a very rare acantholytic disease belonging to the reticulate pigmentary disorders, a group of cutaneous diseases mainly inherited as autosomal dominant [1]. Sporadic cases of GGD have been described [2]. The clin- ical resemblance with Dowling-Degos disease (DDD) and the presence of the same gene mutations in DDD [3] prompts considering GGD and DDD as two distinct phenotypes of the same pathological entity. In GGD mutations in genes KRT5, POFUT1, POGLUT1, or PSENEN, affecting melanosome transfer and melanocyte and keratinocyte differentiation, may account for the polymorphous phenotype. While KRT5 mutation is responsible for classic and generalized DDD and “classic” GGD, mutations in POGLUT1 are described in the general- ized “atypical” GGD phenotype, in which the characteristic flexural lesions are absent and persistent macules are distrib- uted mainly on trunk and extremities [4]. Case Presentation Case 1. A healthy 41-year-old Caucasian female pre- sented with a 2-year history of a slightly pruritic rash af- fecting the trunk. Physical examination revealed thin flat non-folliculotropic papules, some of which scaly, admixed with mottled lentigo-like macules (Figure 1A). The flex- ural areas and the face were spared. Dermoscopy of pap- ular lesions showed a yellowish-to-brown-tan star-like or polygonal central area surrounded with a whitish halo on a faint erythematous background with fine linear-curved vessels at the periphery (Figure 1B). Macular lesions, on the other hand, showed a pseudo-reticular pattern with well demarcated borders (Figure 1C). At histological 2 Research Letter | Dermatol Pract Concept. 2025;15(4):4640 Figure 1. (A) Papular and macular lesions on the trunk in a 41-year-old female. (B) Dermoscopy of a Galli-Galli disease (GGD) papule with a polygonal yellowish center (black arrow), a whitish halo (red arrow), and fine linear and curved vessels at the periphery (asterisk). (C) Dermoscopy of a macule with pseudo-reticular pat- tern and clear-cut borders. (D) Histology of a GGD papular lesion showing subtle focal acantholysis in the stratum spinosum and gran- ulosum (arrow) with rare dyskeratotic keratinocytes (H&E, original magnification ×100). Figure 2. (A) Papular and macular lesions of the limb of a 50-year-old female. (B) Dermoscopy of an almost involute papular lesion show- ing a star-like uniform pinkish center with scales fading to macules with a pseudo-network pattern (black arrow). observed (Figure 2B). Histology of a papular lesion showed the same characteristic as observed in Case 1. Conclusion In GGD, an accurate histopathological examination is nec- essary to identify foci of acantholysis as this clue may be extremely subtle in the atypical, generalized variant, and it is mainly linked to the age of the lesion. Of note, as acanthol- ysis is commonly observed in different dermatoses (Table 1), clinical-pathological correlation is always mandatory. To our knowledge, dermoscopic features of GGD have been only reported by two groups [5,6], which also em- ployed reflectance confocal microscopy and line-field optical coherence tomography, with a good correlation to histolog- ical features, suggesting a reliable non-invasive approach. Thus, the whitish central area and the lentigo-like pattern observed with dermoscopy likely correspond respectively to the hyper-parakeratosis and acanthosis and to the elongate rete ridges seen at histology. The dermoscopic brownish star-like brown pattern with a thin peripheral halo and a pinkish background, along with the absence of follicular plugging and inclusion microcysts, are very characteristic of GGD. Moreover, we showed a pos- sible dermoscopic continuum between the papular and the macular late phase. examination of a papule, elongation of the rete ridges, hyper- parakeratosis, and deceptively focal acantholysis in the stratum spinosum and granulosum with occasional dyske- ratinocytes were present (Figure 1D). The dermis showed a moderate lymphocytic infiltrate. Based on the clinical find- ings and on the histopathological features, the patient was diagnosed with GGD. Case 2. A 50-year-old female presented with a 10- year history of crops of asymptomatic fine erythematous- brownish papular lesions limited to the lower limbs associ- ated with round lentigo-like macules (Figure 2A). Dermo- scopic findings of the papular and the macular lesions were similar to those described in Case 1, but in Case 2, macular lesions prevailed, and “hybrid” papulo-macular lesions were Research Letter | Dermatol Pract Concept. 2025;15(4):4640 3 References 1. Michelerio A, Greco A, Tomasini D, Tomasini C. Galli-Galli disease: a comprehensive review. Dermatopathology (Basel). 2024;11(1):79-100. DOI: 10.3390/dermatopathology11010008 . PMID: 38390850. 2. Sprecher E, Indelman M, Khamaysi Z, Lugassy J, Petronius D, Bergman R. Galli-Galli disease is an acantholytic variant of Dowling-Degos disease. Br J Dermatol. 2007;156(3):572-4. DOI: 10.1111/j.1365-2133.2006.07703.x. PMID: 17300252. 3. Hanneken S, Rütten A, Pasternack SM,  et al. Systematic mutation screening of KRT5 supports the hypothesis that Galli-Galli disease is a variant of Dowling-Degos disease. Br J Dermatol.  2010;163(1):197–200.   DOI: 10.1111/j.1365-2133 .2010.09741.x. PMID: 20222933. 4. Yang A, Cheung K, Kossard S, Murrell DF. Atypical dissem- inated variant of Galli-Galli disease: a review of the litera- ture. Am J Dermatopathol. 2020;42(7):484-90. DOI: 10.1097 /DAD.0000000000001467. PMID: 31449063 5. Coelho de Sousa V, El-Shabrawi-Caelen L, Mendes-Bastos P, Oliveira A. Reflectance confocal microscopy for the diagnosis of Galli-Galli disease. Int J Dermatol. 2017;56(12):1501-04. DOI: 10.1111/ijd.13677. PMID: 28703363. 6. Maione V, Tonon F, Soglia S, Venturuzzo A, Venturini M, Calzavara-Pinton P. Line-field confocal optical coherence tomog- raphy of a suspected case of Galli-Galli disease. Dermatol Pract Con- cept. 2024;14(1):e2024007. DOI: 10.5826/dpc.1401a7. PMID:  38364408. Table 1. Papular Acantholytic/Dyskeratotic Disorders Clinically Mimicking GGD. Disease Diagnostic clues Dowling-Degos disease (DDD) Genetically inherited. Hyperpigmented macules in a reticulate distribution. Dermoscopy may show follicular plugging and milia within papular lesions. Grover disease Itchy papular and vesicular eruption on trunk and proximal extremities. Superficial indentations/micro fissures at dermoscopy. Darier disease Genetically inherited with variable expressivity. Warty itchy lesions on seborrheic areas of the trunk and face. Palmoplantar and nail manifestations. BRAF-inhibitor-induced acantholytic dyskeratosis Oncological patient under treatment. Acantholytic dyskeratotic acanthoma (acantholytic dyskeratoma) Solitary lesions. Superficial indentations/microfissures at dermoscopy.