Clinical, histopathological and immunohistochemical study of keratoacanthoma

Abstract

Keratoacanthoma (KA) is an epithelial tumor of the skin, classically considered as having a malignant transformation risk of 15%; however, many authors and the new World Health Organization (WHO) Classification of skin tumors consider KA as an incipient variant of the cutaneous squamous cell carcinoma (SCC). The aims of the study were to assess the clinical, histopathological (HP) and immunohistochemical (IHC) aspects of the KA and the role of these factors in malignancy occurrence. The studied group comprises 194 patients diagnosed with KA or malignant KA, hospitalized in the Clinic of Dermatology, Emergency County Hospital, Craiova, Romania, between 2006 and 2019. There were 83 males and 111 females, aged 34 to 90 years, 57.21% of the patients being from the rural environment. The histopathology diagnosed 51 KAs and 143 malignant KAs (SCCs). Clinical diagnosis had a limited value in detecting the absence or presence of malignancy in the KA lesion, due to a low accuracy (36.08% and 29.89%, respectively) and specificity (23.07% and 27.02%, respectively); therefore, the HP exam of the surgical excision specimen has a paramount importance in establishing the diagnosis. IHC analysis revealed that the immunostainings for apoptosis-associated proteins and keratinocyte proliferative activity [p53, B-cell lymphoma-2 (Bcl-2), Ki-67 and proliferating cell nuclear antigen (PCNA)] provide some arguments to differentiate between KA and SCC in the studied cases. The correlation of clinical, HP and IHC data lead to an accurate diagnosis of KA; moreover, the clinical, HP and IHC data sustain the idea that KA is a particular form of welldifferentiated SCC, which require an active therapeutic attitude.

Gross, Histologic and Immunohistochemical Characteristics of Keratoacanthomas in Lizards

“…The strong Pan-CK immunostaining (IRS score 9-12) contributes to the delineation of KA margins and assesses the integrity of the basement membrane [45]. In contrast to the moderate COX-2 expression of KAs in the lizards in this study (Figure 7A), strong COX-2 staining was observed in the KA with malignant transformation in panther chameleon 1, similar to what has been described in humans and bird SCCs, indicating increased cell proliferation, angiogenesis, and invasiveness [33,37,43,44,[46][47][48]. Based on these IHC results, COX-2 and E-cadherin staining especially can serve as an important tool in the diagnosis of KA and its differentiation from KA with malignant transformation and SCC in lizards.…”

“…Based on this variation, the World Health Organization (WHO) Classification of skin tumors proposed by the International Agency for Research on Cancer (IARC) categorizes different histologic variants of dermal SCC with acantholytic SCC, desmoplastic SCC and spindle cell SCC representing high-risk histologic variants, and verrucous SCC and KA representing low-risk histologic variants [8,30,31]. KA is defined as a well-differentiated, minimally invasive neoplasia with low metastatic potential [9,32,33]. In contrast to dogs and birds, KA in humans often shows a spontaneous regression phase that may occur within 4-6 months of the initial diagnosis [34].…”

“…If malignant transformation of KA into SCC takes place in humans, it seems to occur within a couple of months of KA development. This transformation is considered to occur spontaneously and is mainly seen in senile skin with actinic degeneration or immunocompromised persons [33]. It is unknown, however, what proportion of human KAs eventually transform into SCC and what the deciding factors for transformation are [34,36,37].…”

Prognostic value of HPV genotyping in cutaneous warts​

“…Keratoacanthoma* Keratoacanthoma is an epithelial tumor with clinical and histopathological features similar to SCC and a progression rate to malignancy of 15%, that has been classified into low-grade SCC in the recent WHO classification of cutaneous tumors (Murphy et al, 2018;Vîlcea et al, 2022).…”