Clear cell acanthoma developing on a psoriatic plaque: further evidence of an inflammatory aetiology?

Clear Cell Acanthoma: A Series of 70 Cases

BACKGROUND AND OBJECTIVE

Clear cell acanthoma (CCA) is an uncommon lesion histologically characterized by the presence of epidermal acanthosis with keratinocytes containing clear cytoplasm. Although many single cases of CCA have been described, few case series have been published. The aim of this study was to describe the clinical characteristics of CCA in our practice setting.

MATERIAL AND METHODS

Retrospective study of patients diagnosed with CCA at Hospital Universitario de Bellvitge in Barcelona, Spain, between 1995 and 2021. We conducted a chart review to record age, sex, number and location of lesions, diameter, time since onset, clinical characteristics, suspected clinical diagnosis, and treatment.

RESULTS

Seventy patients (30 women and 40 men) with a mean (SD) age of 62 (13) years were diagnosed with CCA during the study period. Median (interquartile range) time since onset was 2 (4) years and median lesion diameter was 6 (5) mm. One woman had multiple lesions. Lesions were located on the lower extremities in 57 patients (81%), the posterior aspect of the trunk in 8 (11%), the anterior aspect of the trunk in 4 (5%), and the upper extremities in 1 (1%). CCA was clinically suspected in 40% of patients seen by dermatologists.

CONCLUSIONS

CCA presents as an erythematous, dome-shaped lesion with pinpoint vessels and an epidermal collarette. The accuracy of clinical diagnosis has improved relative to earlier series, possibly due to a better clinical understanding of this lesion and a greater use of dermoscopy.

[Translated article] Clear Cell Acanthoma: A Series of 70 Cases

BACKGROUND AND OBJECTIVE

Clear cell acanthoma (CCA) is an uncommon lesion histologically characterized by the presence of epidermal acanthosis with keratinocytes containing clear cytoplasm. Although many single cases of CCA have been described, few case series have been published. The aim of this study was to describe the clinical characteristics of CCA in our practice setting.

MATERIAL AND METHODS

Retrospective study of patients diagnosed with CCA at Hospital Universitario de Bellvitge in Barcelona, Spain, between 1995 and 2021. We conducted a chart review to record age, sex, number and location of lesions, diameter, time since onset, clinical characteristics, suspected clinical diagnosis, and treatment.

RESULTS

Seventy patients (30 women and 40 men) with a mean (SD) age of 62 (13) years were diagnosed with CCA during the study period. Median (interquartile range) time since onset was 2 (4) years and median lesion diameter was 6 (5)mm. One woman had multiple lesions. Lesions were located on the lower extremities in 57 patients (81%), the posterior aspect of the trunk in 8 (11%), the anterior aspect of the trunk in 4 (5%), and the upper extremities in 1 (1%). CCA was clinically suspected in 40% of patients seen by dermatologists.

CONCLUSIONS

CCA presents as an erythematous, dome-shaped lesion with pinpoint vessels and an epidermal collarette. The accuracy of clinical diagnosis has improved relative to earlier series, possibly due to a better clinical understanding of this lesion and a greater use of dermoscopy.

Pale (Clear) Cell Acanthoma of the Palate

Clear cell acanthoma (CCA), also known as pale cell acanthoma, represents a rare benign epidermal tumor with strong predilection for the lower extremities of middle-aged individuals and no frank gender preference. The etiology of CCA is poorly understood, although a localized psoriasiform reaction is favored. Herein, we report on the clinicopathologic and immunohistochemical features, and HPV status of an apparent example of oral CCA. A 58-year-old female presented with a well-circumscribed, asymptomatic, exophytic, sessile and erythematous nodule of the right hard palate, measuring 0.7 cm in greatest dimension. Microscopically, the lesion featured parakeratosis and acanthosis with neutrophilic microabscesses and broad elongated rete pegs. In areas, spinous epithelial cells exhibited pale or clear cytoplasm without nuclear pleomorphism, mitoses or cytologic atypia. The supporting connective tissue revealed mild chronic inflammation with few scattered neutrophils and numerous capillary vessels. PAS histochemical stain with and without diastase disclosed the presence of cytoplasmic glycogen in the pale cells. The majority of glycogen-rich epithelial cells stained strongly for EMA and were negative for D2-40. Ki-67 immunostaining was confined only to the basal cell layer of the epithelium. A diagnosis of CCA was rendered. The lesion was negative for human papillomavirus (HPV) infection, as assessed by HPV-DNA PCR using the MY09/11 primers for the L1 conserved region, thus HPV infection does not appear to contribute to the pathogenesis of oral CCA. In conclusion, we report an intraoral example of CCA in order to raise awareness about this entity.

Clear cell acanthoma with changes of eccrine syringofibroadenoma: reactive change or clue to etiology?

We observed two patients with solitary lesions showing features of clear cell acanthoma with underlying eccrine syringofibroadenoma-like changes. The pathogenesis of these entities has been debated since their original descriptions, with most recent literature suggesting that both may represent reactive phenomena rather than true neoplasms. Our observation prompted us to perform a retrospective review of clear cell acanthoma cases to determine the frequency of such associated eccrine syringofibroadenoma changes. Of 47 examined cases of clear cell acanthoma, 9 (19%) showed associated changes of eccrine syringofibroadenoma. Immunohistochemical evaluation performed on a subset of cases identified similar but slightly divergent differentiation patterns within the lesions. While epithelial membrane antigen and PAS expression were similar in both components (although slightly different in intensity), the regions resembling eccrine syringofibroadenoma displayed additional immunoreactivities, supporting the presence of two distinct components. We have found that the concurrence of clear cell acanthoma with syringofibroadenomatous changes is more frequent than generally appreciated and suggest that these entities may share derivation from the eccrine apparatus.

Clear cell acanthoma

Clear cell acanthoma (CCA), is an asymptomatic benign lesion of unknown origin and aetiology, which typically presents as a red to brown, dome-shaped papule on the leg. We discuss the case of a patient with an irregular plaque of hypopigmented papules whose diagnosis of CCA was only made by biopsy, and review the characteristic presentation, uncommon variants, locations and associated conditions of this lesion. The diagnosis is based on histopathology and/or immunohistochemistry, but the variable clinical presentation may make diagnosis difficult. The differential diagnosis includes skin tumours and inflammatory and pigmentary dermatoses. The lesions do not regress spontaneously, and excisional removal is the preferred treatment.

Clear cell acanthoma of the areola and nipple: clinical, histopathological, and immunohistochemical features of two Brazilian cases

Clear cell acanthoma or Degos' acanthoma is a distinct disease concerning its clinical, histopathological, and immunohistochemical features. Its pathologic nature - whether neoplastic or reactive - is still under dispute among researchers. The disease shows a chronic course and often presents with a single papulonodular lesion on the lower limbs of adults. However, cases with multiple lesions, sometimes occurring in an eruptive fashion, and with clear variation in the size and shape of the cutaneous lesions have been reported. So far, five cases in which the lesions were exclusively located in the nipple area have been reported, all in Korean women. Four of these cases mimicked eczema and one, a polypoid nodule. The aim of this article is to present clinical, histopathological, and immunohistochemical features of two additional cases in Brazilian women with similar nipple topography.

Clear-cell acanthoma versus acanthosis: a psoriasiform reaction pattern lacking tricholemmal differentiation

Clear-cell acanthoma (CCA) has been reported to be a benign epidermal neoplasm; however, several authors have suggested alternative differentiation as well as other nosologic categories, including a reactive dermatosis. Fourteen CCAs, ten tricholemmomas, and seven cases of psoriasis were reviewed with conventional microscopy, periodic acid-Schiff stains, and immunohistochemical stains. Twelve of fourteen (86%) CCAs were associated with underlying or adjacent conditions. The CCAs stained immunohistochemically in a pattern similar to normal epidermis and psoriasis. Tricholemmomas stained in a distinctly different pattern with MNF116 and NGFR/p75. These cases demonstrate CCA in settings that reflect chronic inflammation, primarily scars and stasis dermatitis, and with an immunophenotype that parallels psoriasis. These findings support the contention that CCA does not show outer follicular sheath (tricholemmal) differentiation. Furthermore, these cases lend additional support to the contention that CCA represents a psoriasiform reaction pattern, which, in appropriately taken biopsies, usually has a demonstrable associated condition. Nonetheless, the precise nosology of this phenomenon has yet to be elucidated completely.

Urachal duct remnant-like umbilical clear cell acanthoma in an infant: an unusual presentation and pitfall in clinical practice

BACKGROUND

Although an umbilical nodule is common in neonates and young infants, an umbilical nodule of poor therapeutic response will increase the likelihood of other uncommon etiology. Clear cell acanthoma (CCA) has never been described as an oozing umbilical nodule on infants.

METHODS

To present a case of CCA which occurred on an 8-month-old female infant presenting with one weeping nodule on the umbilicus since early neonate. The lesion underwent skin biopsy and subsequent hematoxylin-eosin and periodic acid-Schiff staining.

RESULT

Three courses of liquid nitrogen cryosurgery were performed after the diagnosis of CCA was confirmed. The lesion resolved rapidly.

CONCLUSION

This report presents the first and youngest case of umbilical CCA in the English literature. This case supports the inflammatory dermatosic nature of CCA.

Expression of keratinocyte growth factor and its receptor in clear cell acanthoma

The aetiopathogenic mechanism underlying clear cell acanthoma (CCA) is not completely clear and it has been postulated that CCA and psoriasis may have a similar pathogenesis because of the common features shared by the two diseases. As it has been recently demonstrated that in psoriatic lesions the paracrine epithelial growth factors [keratinocyte growth factor (KGF)/fibroblast growth factor (FGF)-7 and FGF-10] are involved in promoting and sustaining the keratinocyte hyperproliferation, the aim of this study was to analyse the expression of KGF on CCA lesions and to search for a role of this growth factor in CCA pathogenesis. Immunohistochemical analysis showed an up-modulation of KGF in CCA, although the immunostaining was variable among the different samples collected. Positive immunoreactivity for KGF was detected mainly on dermal areas where the inflammatory infiltrate was more pronounced suggesting a relationship between lymphocyte activation and KGF up-modulation. Real-time quantitative RT-PCR assay performed on mRNA extracted from formalin-fixed paraffin-embedded CCA and normal skin (NS) samples further demonstrated the overexpression of the KGF/FGF-7 gene in all CCA samples compared with NS. Moreover, the evaluation by immunohistochemistry of KGF receptor distribution, the high-affinity tyrosine kinase receptor for KGF, showed a down-modulation of this receptor, as previously reported in the presence of increased levels of KGF. Taken together these results suggest the inflammatory nature of CCA and further support the hypothesis that this disease may represent, like psoriasis, an inflammatory dermatosis in which KGF up-modulation may be responsible for keratinocyte hyperproliferation and may represent a new common feature of both diseases.

Clear cell acanthoma successfully treated with a carbon dioxide laser

BACKGROUND

The treatment of choice for clear cell acanthoma (CCA) is excision. Resolution after cryotherapy has also been reported but requires three to four courses of treatment.

OBJECTIVE

To demonstrate three CCA lesions in two patients successfully treated with a carbon dioxide (CO2) laser.

METHODS

Under local anesthesia, these lesions were vaporized by using a CO2 laser in the Silktouch mode with a spot size of 5 mm and a fluence of 20 J/cm2. Two to six passes, as needed, were delivered until the tumor was completely removed.

RESULTS

Pain was minimal or nonexistent during and after the operation. No postoperative edema was noted. The wounds healed satisfactorily without scarring. No sign of recurrence was found following operation.

CONCLUSION

The CO2 laser has the advantages of requiring only one course, precise tumor removal, a relatively bloodless surgical field, a short operation time, and less or no postoperative pain and edema. Postoperative wound care is convenient and easy with hydrocolloid and alginate dressings. The patient's quality of life is less adversely affected. The CO2 laser may be appropriate for multiple CCAs, giant CCA, CCA overlying or near joints, CCA refractory to cryotherapy, patients on anticoagulants, and those who cannot tolerate pain from cryotherapy, especially children and the elderly.

Psoriasis-like dermoscopic pattern of clear cell acanthoma

BACKGROUND

Dermoscopy provides additional criteria for the diagnosis of skin lesions.

OBJECTIVE

To investigate the dermoscopic aspect of clear cell acanthoma (CCA).

METHODS

Six consecutive cases of CCAs were observed under conventional dermoscopy (Case 1-4) or videodermoscopy (Case 5-6).

RESULTS

Common dermoscopic findings were: (i) squamous surface with translucid collarette; (ii) dilated capillary loops, mainly perpendicularly orientated to the skin surface, as dotted, pinpoint-like structures, regularly distributed in a reticular array over the surface.

CONCLUSIONS

The vascular psoriasis-like dermoscopic findings seem to be a clue for CCA and provide evidence of an inflammatory process for CCA formation.