Clinical features and histologic pattern analysis of pigmented basal cell carcinomas in an Italian population

Factors associated with residual tumor at time of Mohs micrographic surgery for basal cell and squamous cell carcinomas

BACKGROUND

Residual tumor is not always clinically apparent following biopsy of cutaneous carcinomas, which may prompt patients to question the need for definitive treatment.

OBJECTIVE

We investigated the percentage of cases in which residual tumor was histologically present at the time of Mohs micrographic surgery (MMS) for basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) and investigated factors associated with residual tumor.

METHODS

We examined 483 MMS cases performed for biopsy-proven BCC (n = 287) and SCC (n = 196) between October 2022 and April 2023. Single-stage MMS specimens were step-sectioned en face to exhaust the block. Univariate and multivariable logistic regression models were created.

RESULTS

Residual tumor was identified in 83.3% of BCC and 66.8% of SCC at the time of MMS (P = .01). In patients clinically appearing tumor-free following biopsy, residual histologic tumor was identified in 68.2% of BCC and 41.5% of SCC. Residual tumor was significantly more likely in men (P = .04), high-risk sites (P = .002), smaller biopsy sizes (P = .0003), and larger preoperative sizes (P < .0001).

LIMITATIONS

Single center, retrospective cohort.

CONCLUSION

The majority of patients with BCC and SCC have residual histologic tumor at the time of MMS, oftentimes even when tumor is not clinically apparent. Multiple factors impact the presence/absence of residual tumor.

Dermoscopic and Histopathologic Analysis of the Correlation between the Pigmentation of Basal Cell Carcinoma and Tumor Aggressiveness

BACKGROUND

Basal cell carcinoma (BCC) is the most common type of skin cancer. In patients with darker skin, most BCCs are pigmented. Studies suggest that increased pigmentation in BCC may be inversely associated with tumor aggressiveness.

OBJECTIVE

This study analyzed the dermoscopic features and histopathologic patterns of BCCs to evaluate the correlation between BCC pigmentation and tumor aggressiveness.

METHODS

A total of 76 BCC lesions were included in this retrospective study. The Mohs micrographic surgery (MMS) stage and tumor depth were measured as indices of tumor aggressiveness. The Fontana-Masson stain was performed for the identification of melanin, and immunohistochemical analysis was performed using Melan-A and HMB-45 to identify melanocytes.

RESULTS

In MMS stage 1, the dermoscopic pigmentation value was 34.48%±14.22% (mean±standard deviation). In MMS stages 2 and 3, dermoscopic pigmentations were 13.72%±7.54% and 15.50%±17.52%, respectively. In the logistic regression model, higher dermoscopic pigmentation (95% confidence interval [CI], 0.68~0.99), melanin (95% CI, 0.63~0.89), and melanocyte-stained areas (95% CI, 0.70~0.92) were associated with a lower possibility of BCC tumor infiltration over the middle and lower layers.

CONCLUSION

We found an inverse correlation between the pigmentation and aggressiveness of BCCs. Clinicians can predict the subclinical infiltration depth of BCC on the basis of the pigmentation observed on dermoscopy. Pigmentation can be considered a favorable prognostic factor for BCC.

Diagnostic accuracy of dermoscopy for 934 basal cell carcinomas: A single-center retrospective study

Although the efficacy of dermoscopic diagnosis of basal cell carcinoma (BCC) has already been established, most studies have been conducted in Western countries. However, there are racial differences in the clinicopathological characteristics of BCC, highlighting the need for a survey among Asians. Herein, we aimed to investigate the diagnostic accuracy of dermoscopy in 934 Japanese patients with BCC and statistically analyze the clinicopathological factors affecting diagnostic accuracy. We analyzed 5093 skin lesions, including 934 BCCs that were diagnosed consecutively from 1998 to 2018. The sensitivity and specificity of dermoscopic diagnosis for BCC were calculated. The sensitivity and specificity of dermoscopic diagnosis were 92.2% and 96.0%, respectively. There were 73 false-negative cases of BCCs that were clinically diagnosed with other diseases. The most common incorrect clinical diagnosis was seborrheic keratosis (n = 18), followed by melanocytic nevus (n = 15). Multiple logistic regression analysis showed that sensitivity was significantly lower in BCCs located on the trunk and extremities, which showed low pigmentation (less than 10% of the lesion surface) and were diagnosed by a resident dermatologist. Experience of 3-6 months of 12 resident dermatologists revealed increased sensitivity. Dermoscopy is a reliable tool for the accurate diagnosis of BCC in Japanese individuals. Care should be taken when diagnosing BCCs of the trunk and extremities, and the less-pigmented subtype because of lower sensitivity. A certain amount of experience is required to improve the skills for dermoscopy.

Clinical, Dermoscopic and Histopathological Evaluation of Basal Cell Carcinoma

INTRODUCTION

Dermoscopy aids in identifying histopathological subtypes and the presence of clinically undetectable pigmentation in basal cell carcinoma (BCC).

OBJECTIVES

To investigate the dermoscopic features of BCC subtypes and better understand non-classical dermoscopic patterns.

METHODS

Clinical and histopathological findings were recorded by a dermatologist who was blinded to the dermoscopic images. Dermoscopic images were interpreted by two independent dermatologists blinded to the patients' clinical and histopathologic diagnosis. Agreement between the two evaluators and with histopathological findings was evaluated using Cohen's kappa coefficient analysis.

RESULTS

The study included a total of 96 BBC patients with 6 histopathologic variants: nodular (n=48, 50%), infiltrative (n=14, 14.6%), mixed (n=11, 11.5%), superficial (n=10, 10.4%), basosquamous (n=10, 10.4%), and micronodular (n=3, 3.1%). Clinical and dermoscopic diagnosis of pigmented BCC showed high agreement with histopathological diagnosis. The most common dermoscopic findings according to subtype were as follows: nodular BCC: shiny white-red structureless background (85.4%), white structureless areas (75%), and arborizing vessels (70.7%); infiltrative BCC: shiny white-red structureless background (92.9%), white structureless areas (78.6%), arborizing vessels (71.4%); mixed BCC: shiny white-red structureless background (72.7%), white structureless areas (54.4%), and short fine telangiectasias (54.4%); superficial BCC: shiny white-red structureless background (100%), short fine telangiectasias (70%); basosquamous BCC: shiny white-red structureless background (100%), white structureless areas (80%), keratin masses (80%); micronodular BCC: short fine telangiectasias (100%).

CONCLUSIONS

In this study, arborizing vessels were the most common classical dermoscopic feature of BCC, while shiny white-red structureless background and white structureless areas were the most frequent non-classical dermoscopic features.

Periocular Pigmented Basal Cell Carcinomas: Clinicopathologic Features and Mutational Profile

PURPOSE

Pigmented basal cell carcinomas (PBCC) is an uncommon variant of basal cell carcinoma of the periocular region with limited information in the literature. We highlight the clinicopathological profile and somatic mutations in periocular PBCC.

METHODS

The clinicopathological features and somatic mutations in patients with periocular PBCC were examined and compared with periocular non-PBCC reported in the literature. Next-generation sequencing panel analysis for the excised tumors identified somatic mutations.

RESULTS

In a total of 31 patients, PBCC was common in females (54%; p = 0.03); as a unilateral lower eyelid (n = 22; 71%), solitary mass (n = 30; 98%). Pathologic subtypes were variable. Most were nodular or mixed variants (n = 23; 74%). During the follow up (2.5-4.5 years), 1 patient (3.5%) had a recurrence. The clinical and pathologic features of PBCC were similar to those reported in nonperiocular locations. Somatic mutations detected in 25/31 tumors. Variants in 50/161 genes in the panel were noted. PTCH1 (14/31), TERT (12/31), and SMO (7/31) variants were common. Fifteen patients had novel drivers, including POLE, FANCD2, and CREBBP. SMO mutations were significantly more common in females (7/7), lower eyelid (5/7), and TERT mutations were more common in nodular subtype (10/12).

CONCLUSIONS

In this large cohort of a relatively uncommon variant of BCC, the clinicopathological features and tumor behavior of PBCC was similar to periocular non-PBCC. The somatic mutation spectrum of PBCC resembles that reported in nonperiocular cutaneous BCC with novel drivers identified. We identified several potential actionable mutations that could be targeted with molecular therapy.

Evidence from Clinical Studies Related to Dermatologic Surgeries for Skin Cancer

Simple Summary

Although significant progress in pharmacotherapy for skin cancer has been made in the past several years, surgical removal of primary skin cancer is still the first choice of treatment unless distant metastases are evident. In the surgical treatment of primary skin tumors, the surgical margin is critical not only for reducing the possibility of tumor recurrence but also for minimizing the cosmetic and functional complications associated with wide local excision. In contrast, dermatologic surgeries including lymph node dissection and skin graft can cause various complications, and these complications are frequently associated with significant morbidity and discomfort. In this review, we summarize the evidence from previous clinical studies regarding the optimal surgical margin for skin cancer and the methods for diminishing the complications associated with dermatologic surgery.

Abstract

Despite the significant progress made in the past several years in pharmacotherapies for skin cancer, such as BRAF/MEK inhibitors, immune checkpoint inhibitors, and Hedgehog pathway inhibitors, surgical removal of primary skin cancer is still the first choice of treatment unless distant metastases are evident. In cases of lymph node metastases with clinically palpable lymphadenopathy, lymph node dissection (LND) is typically performed for most skin cancers. In the surgical treatment of primary skin tumors, the surgical margin is critical not only for reducing the possibility of tumor recurrence but also for minimizing the cosmetic and functional complications associated with wide local excision. In contrast, dermatologic surgery can cause various complications. Although skin graft is frequently used for reconstruction of the surgical defect, extensive graft necrosis may develop if optimal stabilization of the graft is not obtained. LND also sometimes causes complications such as intraoperative or postoperative bleeding and postoperative lymphoceles. Moreover, as in other types of surgery, surgical site infection, intraoperative anxiety, and intraoperative and postoperative pain may also develop. These complications are frequently associated with significant morbidity and discomfort. In this review, we summarize the evidence from previous clinical studies regarding the optimal surgical margin for skin cancer and the methods for diminishing the complications associated with dermatologic surgery.

Recent reductions in the size of facial pigmented basal cell carcinoma at diagnosis and the surgical margin: A retrospective and comparative study

The present, retrospective, single-center study analyzed various factors associated with primary basal cell carcinoma (BCC) in the period before and after the introduction of dermoscopy (BD and AD, respectively). The demographic data of patients with primary BCC between 2001 and 2005 (BD: 84 patients, 90 cases) and 2011 and 2018 (AD: 297 patients, 320 cases) were analyzed. In the pigmented BCC-predominant cohort (94%), the proportion of smaller tumors as well as the total number of tumors significantly increased during AD (median tumor size, 10.0 mm in BD, 8.0 mm in AD; Mann-Whitney U-test, p = 0.011). BCC were excised with a significantly narrower margin during AD (median, 2.0 mm) than during BD (median, 3.0 mm; Mann-Whitney U-test, p < 0.001; odds ratio, 0.30; multivariate logistic regression analysis, p < 0.001); the incomplete excision rate was 1.9%, and the recurrence rate was 0%. The present study suggests that the introduction of dermoscopy might have aided in the early diagnosis of smaller BCC, especially in the face region, and determining the appropriate surgical margin. The smaller pigmented BCC can be excised with a narrower margin than stated in the guidelines (4 mm).

Head and neck cutaneous basal cell carcinoma: what should the otorhinolaryngology head and neck surgeon care about?

Cutaneous basal cell carcinoma (cBCC) is the most common malignancy diagnosed in the human population. cBCC presents an increasing incidence which, in the near future, will be higher than all other cancers combined. The majority of cBCC are located in the head and the neck. A diversity of management modalities is currently available; nonetheless, surgical excision remains the main modality of treatment. cBCC rarely metastasises and presents a low mortality rate. cBCC morbidity is influenced by local invasion and destruction, especially in the face, where function and aesthetics are major issues. Easy accessibility to the face and skin on the neck makes cBCC an important issue for otorhinolaryngology head and neck surgeons who must be aware and committed in its management, as the main modality of treatment continues to be surgical. The aim of this review is to present a brief and practical overview of head and neck cBCC management for ear, nose and throat (ENT) surgeons, discussing key issues about its epidemiology, risk factors, diagnosis and pathogenesis.

Dermoscopy in the diagnosis and management of basal cell carcinoma

The dermoscopic findings of basal cell carcinoma (BCC) were first described more than a decade ago and the list of BCC-related criteria has been several times updated and enriched. Today, the dermatoscope is considered the key tool for the diagnosis of BCC, since it allows its early detection and enables its discrimination from other pigmented and nonpigmented skin tumors. The dermoscopic pattern of BCC results from several combinations of well-known BCC criteria, depending on several factors, including histopathologic subtype, location, gender, age and pigmentary trait. In addition, recent evidence highlighted that dermoscopy is also useful in the management of BCC, since it provides information on the tumor subtype, the presence of pigmentation or ulceration and the response to nonablative treatments.

Narrow-margin excision is a safe, reliable treatment for well-defined, primary pigmented basal cell carcinoma: an analysis of 288 lesions in Japan

BACKGROUND

Complete excision is the most promising treatment for basal cell carcinoma (BCC) and a surgical margin of at least 4 mm is recommended. However, little is known about the appropriate surgical margin of pigmented BCC.

OBJECTIVE

To investigate the reliability of narrower margin excision of well-defined, pigmented BCC.

METHODS

We identified a total of 263 patients with 288 well-defined, primary pigmented BCC at the Department of Dermatology, Kyushu University (Fukuoka, Japan), between January 2006 and December 2013. All lesions were surgically excised with 1-6-mm margins and analysed. For 30 recent lesions out of the 288 lesions, border gaps between dermoscopy and histopathology were assessed.

RESULTS

Of the 288 lesions, 218 (75.7%) were excised with a narrow margin (≤ 3 mm) and 60 lesions (24.3%) with a wide margin (≥ 4 mm). Only two lesions (0.7%), which were excised with 2-mm margins, were associated with tumour-positive margins. Narrow-margin excision showed a complete removal rate of 99% (2-mm margins, 95.3%; 3-mm margins, 100%). Dermoscopically determined borders almost exactly corresponded to the histopathological ones; 71.2% of border gaps between dermoscopy and histopathology were within 1 mm and there were no cases in which tumours spread beyond 1 mm of their dermoscopic borders.

CONCLUSION

Surgical excision with a 2-3-mm margin is reliable treatment for well-defined, primary pigmented BCC, with a complete removal rate of 99%.

The dermatoscopic universe of basal cell carcinoma

Following the first descriptions of the dermatoscopic pattern of basal cell carcinoma (BCC) that go back to the very early years of dermatoscopy, the list of dermatoscopic criteria associated with BCC has been several times updated and renewed. Up to date, dermatoscopy has been shown to enhance BCC detection, by facilitating its discrimination from other skin tumors and inflammatory skin diseases. Furthermore, upcoming evidence suggests that the method is also useful for the management of the tumor, since it provides valuable information about the histopathologic subtype, the presence of clinically undetectable pigmentation, the expansion of the tumor beyond clinically visible margins and the response to non-ablative treatments. In the current article, we provide a summary of the traditional and latest knowledge on the value of dermatoscopy for the diagnosis and management of BCC.

Epidemiology of basal cell carcinoma

Basal cell carcinoma is the most common malignant neoplasm in humans and its incidence has increased over the last decades. Its high frequency significantly burdens the health system, making the disease a public health issue. Despite the low mortality rates and the rare occurrence of metastases, the tumor may be locally invasive and relapse after treatment, causing significant morbidity. Exposure to ultraviolet radiation is the main environmental risk factor associated with its cause. However, other elements of risk are described, such as light skin phototypes, advanced age, family history of skin carcinoma, light eyes and blond hair, freckles in childhood and immunosuppression. Behavioral aspects such as occupational sun exposure, rural labor and sunburns at a young age also play a role. Between 30% and 75% of the sporadic cases are associated with patched hedgehog gene mutation, but other genetic changes are also described. The tumor is commonly found in concomitance with skin lesions related to chronic sun exposure, such as actinic keratoses, solar lentigines and facial telangiectasia. The prevention of basal cell carcinoma is based on the knowledge of risk factors, early diagnosis and treatment, as well as on the adoption of specific measures, particularly in susceptible populations. The authors present a review of the epidemiology of basal cell carcinoma.

Subclinical infiltration of Basal cell carcinoma in asian patients: assessment after mohs micrographic surgery

BACKGROUND

Several differences in basal cell carcinomas (BCCs) were found, according to the ethnic group; for example, pigmented BCCs was more common in Asian or Hispanic patients. However, there are few reports on the subclinical extension of the BCC in Asian patients.

OBJECTIVE

The aim of this study was to evaluate the subclinical infiltration of the basal cell carcinoma in Asian patients.

METHODS

All patients with BCC who visited the department of dermatology at Korea University Ansan Hospital were treated with Mohs micrographic surgery. In 81 patients, 83 tumors of BCC were completely eradicated by Mohs micrographic surgery (MMS) from April 2001 to August 2008, and were reviewed in this study. Information recorded included the total margin and the number of stages of Mohs micrographic surgery, anatomic location, tumor size, presence of pigmentation, clinical type, and pathological subtype. We divided the clinical types into nodular, ulcerated, and pigmented, and the pathological types into nodular, micronodular, morpheaform, and adenoid. The BCC was of pigmented type if pigmentation covered more than 25% of the tumor, regardless of whether pigmentation was distinct, or if there was apparent pigmentation that covered more than 10% of the tumor.

RESULTS

The nose and cheek were the most common sites requiring more than one stage of surgery. In tumors smaller than 1 cm, 91.7% required only one stage of excision, compared with 60.6% in tumors larger than 1 cm. More than two Mohs stages were required in 25% of non-ulcerated BCCs and in 46.2% of ulcerated BCCs. Sixty eight percent of pigmented BCCs required only one stage of Mohs micrographic surgery. In cases of non-pigmented BCCs, only 45% required one Mohs stage. More than one Mohs stage was required in 19.2% of non-aggressive BCCs and in 42.9% of aggressive BCCs.

CONCLUSION

Subclinical infiltration differed between the two groups according to the size of the BCC (1 cm threshold) and most of the BCCs were located in the head and neck area. Considering this result, indication for MMS can be extended for BCCs larger than 1 cm in Asian patients. Ulcerated BCCs required more Mohs stages than non-ulcerated BCCs. Pigmented BCCs might show lesser subclinical infiltration than non-pigmented BCCs. Aggressive pathological subtypes showed more subclinical infiltration than the non-aggressive types; however, after evaluation of the border that was excised with MMS, mixed histologic types were found to be more frequent than generally accepted. Therefore, we consider that, when planning surgery, dermatologists should not place too much confidence in the pathologic subtypes identified by biopsy.

Corrective eyeglasses and medial canthal basal cell carcinoma: a case-control study

BACKGROUND

Corrective eyeglasses are frequently worn by adults, particularly at older ages. Their lenses and frames provide ultraviolet protection. Medial canthal basal cell carcinomas are infrequent (3-8%), and their relation with the use of corrective glasses was not yet investigated.

OBJECTIVES

To assess the prevalence of corrective eyeglasses use in individuals with medial canthal basal cell carcinoma.

METHODS

Case-control study using two controls matched by age, gender, and ethnicity for each case. Cases were patients with medial canthal basal cell carcinoma, and controls were patients with basal cell carcinoma elsewhere on the face. The prevalence of major risk variables was estimated and adjusted by conditional multiple logistic regression.

RESULTS

Fifty cases and 100 controls were assessed. The mean patient age was 69.7 years, and 54% of the subjects were females. No difference regarding the eyeglasses use or use duration was found between groups. However, when visual defects were separately evaluated, eyeglasses for myopia correction were independently associated with lower risk of medial canthal basal cell carcinoma development (OR=0.26; P=0.03), what can be related to long term local photoprotection.

CONCLUSION

The use of eyeglasses for myopia correction is associated with lower prevalence of medial cantal basal cell carcinoma. Risk-reducing mechanisms should be elucidated.

Pigmentation, Melanocyte Colonization, and p53 Status in Basal Cell Carcinoma

Basal cell carcinoma (BCC) is the most common neoplasm in the Caucasian population. Only a fraction of BCC exhibits pigmentation. Lack of melanocyte colonization has been suggested to be due to p53-inactivating mutations in the BCC cells interfering with the p53-proopiomelanocortin pathway and the production of alpha melanocyte-stimulating hormone in the tumor. To evaluate this, we determined tumor pigmentation as well as expression of melan-A and of p53 in 49 BCC tissues by means of immunohistochemistry. As expected, we observed a positive relation between tumor pigmentation and melan-A positive intra-tumoral melanocytes. Melanocyte colonization and, to a lesser extent, p53 overexpression showed intraindividual heterogeneity in larger tumors. p53 overexpression, which is indicative of p53 mutations, was not correlated to melanocyte colonization of BCC. Sequencing of exon 5–8 of the p53 gene in selected BCC cases revealed that colonization by melanocytes and BCC pigmentation is neither ablated by p53 mutations nor generally present in BCCs with wild-type p53.

Dermoscopic evaluation of vascular structures of various skin tumors in Japanese patients

Dermoscopic analysis of skin tumor has been mainly focused on pigmented structures. Recently, several different morphological types of vessels were found to be well associated with pigmented or non-pigmented skin tumors in white subjects. Therefore, the recognition of such vascular structures has been applied for diagnostic purposes. As little statistical information on the various pigmented skin tumor vessels of Japanese patients has been reported, we therefore tried to evaluate the association between various vascular structures and 741 tumor lesions of Japanese patients. Vascular structures were dermoscopically recognized in 41 of 102 cases of melanoma, 104 of 119 basal cell carcinoma (BCC), 86 of 257 seborrheic keratosis (SK), 35 of 210 dermal and compound nevus (DN/CN), six of 12 squamous cell carcinoma (SCC) and 16 of 41 Bowen disease (BD). The structures of arborizing and glomerular vessels statistically revealed diagnostic specificity for BCC and BD, respectively, and hairpin vessels were helpful for differentiating SK from other pigmented tumors, as already reported in white patients. The most common vascular pattern observed in melanoma was the linear-irregular structure, but this pattern in Japanese patients had less diagnostic value than in white patients, because its sensitivity was not significantly higher than in SCC. The most remarkable differences between our study and previous reports with white patients were low frequency and sensitivity of dotted, comma and polymorphous vessels in lesions of melanoma, BCC and DN/CN; these vessels had less diagnostic value for Japanese patients. Finally, the frequency of vascular structures observed in melanoma rose along with the increase of the Breslow's tumor thickness, and 88% of melanomas with vascular vessels revealed tumor thicknesses of more than 2 mm.

Melanization in basal cell carcinomas: microscopic characterization of clinically pigmented and non-pigmented tumours

Clinical and microscopic pigmentation may affect the treatment outcomes in basal cell carcinoma. However, there have not been any in-depth histopathological comparisons between clinically pigmented and non-pigmented basal cell carcinomas with regards to microscopic melanization. The aims of our study were to determine the proportion of pigmented basal cell carcinomas presenting to the National Skin Centre in Singapore, to characterize the histological pattern of melanization and to perform a semi-quantitative analysis of the degree of microscopic melanization of the tumours. Patients with clinical features and histologically confirmed basal cell carcinomas were recruited. Demographic data and clinical characteristics were recorded and basal cell carcinoma sections were examined for histological subtype and pattern of melanization. Twenty-five Chinese patients with 30 basal cell carcinomas were recruited. Three of the five clinically non-pigmented and all of the clinically pigmented basal cell carcinomas had microscopic evidence of melanization. Microscopic melanization in clinically non-pigmented basal cell carcinomas was present only focally or in the centre of the tumour mass. Both groups of basal cell carcinomas may be colonized by melanocytes. Two morphological types of melanocytes, a dendritic and round cell type, were identified. Future research is required to evaluate if the degree of microscopic melanization influences the treatment outcome of basal cell carcinomas.

Sub-populations of melanocytes in pigmented basal cell carcinoma: a quantitative, ultrastructural investigation

BACKGROUND

Pigmentation is a characteristic clinical feature of basal cell carcinomas (BCCs) in Japanese patients. The pathogenesis of melanin pigment in pigmented BCCs is poorly understood.

METHODS

We have combined the techniques of morphometric analysis and electron microscopy to assess accurately the morphologic aspects of melanocytes that occurred in pigmented and non-pigmented areas of pigmented BCCs.

RESULTS

In the pigmented areas melanocytes were not only located along the basal membrane but also interspersed between tumor cells in the central parts of the tumor nest, and had large and numerous dendrites. Those in a supra-basal location displayed some degree of degeneration due to mitochondrion and melanosome swelling. In the non-pigmented areas melanocytes were only basally located, showed fewer dendrites, and frequently showed abortive melanosomes. However, melanocytes in these two different portions were in the active state of melanogenesis and proliferation. Ultrastructural cytomorphometric analysis also showed significant differences in most of the nuclear and cell parameters including nuclear and cell area, the nuclear/cell area ratio, cell perimeter and cell form factor between these two types of melanocytes. Particularly melanocytes in the pigmented areas were twice the cell size of the latter. In addition, the melanosomes remained almost completely in the apoptotic tumor cells, and the phagocytosis of the melanosome-containing apoptotic cells by the neighboring tumor cells appeared to be followed by the formation of the melanosome complexes.

CONCLUSIONS

These findings suggest that different populations of melanocytes are probably present in pigmented BCCs, and repeated cycles of phagocytosis of melanosome-containing apoptotic cells may represent the predominant way of forming large melanosome complexes. The present morphological observation and quantitative analysis provide a morphological basis for further studies to interpret other pathologic changes in pigmented BCCs.