Familial basaloid follicular hamartoma: lesional characterization and review of the literature

Basaloid follicular hamartoma (BFH) is a rare cutaneous lesion associated with the acquisition of small papules that remain stable for many years. Basaloid follicular hamartoma lesions can present sporadically or as part of an inherited syndrome. Occasionally, biopsies of BFH lesions are interpreted as basal cell carcinoma (BCC), which necessitates complete removal of the lesion. In this report, we characterize a case of a familial BFH syndrome and discuss the clinical, histologic, and molecular features of BFH lesions that help to distinguish it from BCC. The BFH lesions in our patients remained stable for many years. Histologically, BFH lesions exhibit fewer mitoses and decreased single cell necrosis when compared with BCC. Immunohistochemical staining for the proliferation markers proliferating cell nuclear antigen and Ki-67 demonstrated less staining in BFH than in BCC. In addition, levels of PTCH (patched) mRNA were increased relative to unremarkable epidermis in familial BFH lesions but to a lesser degree and in a different pattern than that seen in BCC. In summary, familial BFH can be distinguished from BCC based on clinical, histologic, and molecular features and is associated with deregulation of the PTCH pathway. Basaloid follicular hamartoma may represent an indolent lesion within the spectrum of basaloid epithelial neoplasms associated with deregulation of the PTCH signaling pathway. We discuss this case in parallel with a growing body of literature that supports the nosologic designation of BFH.     

Basal cell carcinoma in association with multiple trichoepitheliomas

We report the case of a basal cell carcinoma (BCC) associated with multiple trichoepitheliomas (TEs) and include the results of histopathological and immunohistochemical studies. The patient had a large, pigmented nodule associated with 4 flesh-colored papules in the central facial area. Two of the 4 flesh-colored papules and the large pigmented nodule were excised. Histopathologically, the pigmented nodule was diagnosed as BCC and 2 of the papular lesions were diagnosed as TEs. In both the BCC and TEs, almost all of the basaloid aggregations were diffusely positive for cytokeratin (CK) 19, CK8 and CK8/18. Based on these clinicopathological observations and reports in the recent literature, these two neoplasms are considered to be highly related. BCC appears to differentiate toward follicular germinative cells, and TE is its benign counterpart.     

Basaloid squamous cell carcinoma with 'monster' cells: a mimic of pleomorphic basal cell carcinoma

Pleomorphic giant or 'monster' cells represent a well-recognized yet uncommon finding associated with basal cell carcinoma (BCC), usually of nodular type. We present a case of basaloid squamous cell carcinoma (basaloid SCC) with 'monster' cells that closely mimicked those described in pleomorphic nodular BCC. Clinically, the lesion presented as a fleshy, hyperkeratotic nodule in an 82-year-old woman. Histopathology revealed a basaloid lesion with lobulated borders and focal retraction artifact but a lack of prominent palisading or stromal mucin. There were areas of necrosis and small foci of keratinization. Striking bizarre monstrous pleomorphic nuclei were widely scattered throughout the lesion. Ber-EP4 immunohistochemistry proved to be negative and epithelial membrane antigen (EMA) expression was moderate to strong in 70% of the basaloid epithelium. Monster cells have not previously been highlighted in cutaneous SCC or in its uncommon cutaneous basaloid variant. The prognostic significance of monster cells is unknown but, given the relative paucity of keratinization in basaloid SCC, these lesions should probably be regarded as poorly differentiated. We have not previously encountered an SCC that so closely resembles nodular BCC with pleomorphic monster cells and believe that this is the first such report in the literature.     

Bcl-2, CD34 and CD10 expression in basaloid follicular hamartoma, vellus hair hamartoma and neurofollicular hamartoma demonstrate full follicular differentiation

Generalized basaloid follicular hamartoma syndrome (GBFHS) is a rare, recently-described, autosomal-dominantly inherited disorder that presents with disseminated milia, palmoplantar pitting, hypotrichosis and basaloid follicular hamartomas (BFH). BFH is a benign adnexal tumor that resembles basal cell carcinoma (BCC). In this study, we report two cases of GBFHS and stain BFH, a vellus hair hamartoma (VHH) and a neurofollicular hamartoma (NH) with CD34, bcl-2 and CD10 to characterize and compare the staining patterns of these follicular tumors. Standard immunohistochemistry labeling with CD34, bcl-2 and CD10 was performed on paraffin-embedded, formalin-fixed tissue sections of five BFH (four for CD10), one VHH and one NH. CD34 stromal staining was observed in all specimens. Bcl-2 stained the outermost cell layers of the basaloid nests in all specimens. CD10 stained the peritumoral stroma of all specimens. The BFH, NFH and the VHH showed CD10 staining of matrical cells. CD34 and CD10 stain peritumoral stroma of BFH, VHH and NH. Bcl-2 stains the outermost cell layer of these tumors. CD10 was also observed to stain matrical cells. These results show the similarities in differentiation between these benign follicular neoplasms and trichoepithelioma.     

Basal Cell Carcinoma With Matrical Differentiation in a Transplant Patient: A Case Report and Review of the Literature

Background: Shadow cells are characteristic of pilomatricoma, a distinct neoplasm of hair matrix differentiation. Shadow cells within an otherwise classic basal cell carcinoma (BCC) has been referred to as "BCC with matrical differentiation". We present a case of BCC with matrical differentiation in a transplant patient. To our knowledge, none have been reported arising on the background of immunosuppression. Methods: A 58‐year‐old male cardiac transplant patient had a left hand nodule, which was excised and submitted for routine histologic review. Results: The lesion revealed multiple basaloid tumor masses. In some areas, there was peripheral palisading with stromal retraction artifact, typical of basal cell carcinoma, extending into the deep reticular dermis. The tumor also contained a population of shadow cells, similar to those in pilomatricoma, with basaloid cells in the periphery. Trichohyaline granules were identified in many of the tumor cells. These granules are a hallmark of follicular matrix differentiation. Mitoses were rare. There was no evidence of an infiltrating growth pattern. Conclusion: Basal cell carcinoma with matrical differentiation is a rare subtype of basal cell carcinoma featuring shadow cells, such as those typically seen in pilomatricoma. This tumor has not yet been reported in an immunosuppressed transplant patient.     

Basal cell carcinoma with matrical differentiation in a transplant patient: a case report and review of the literature

BACKGROUND: Shadow cells, characterized by basaloid squamous cells with a distinct well-defined border and a central unstained area as a shadow of lost nuclei, are characteristic of pilomatricoma, a distinct neoplasm of hair matrix differentiation. The presence of shadow cells within tumor islands composed of follicular germinative cells of an otherwise classic basal cell carcinoma (BCC) has been considered as a distinct diagnostic category of BCC with matrical differentiation. We present a case of BCC with matrical differentiation in a transplant patient. To our knowledge, only 10 cases [Aloi et al. Am J Dermatopathol 1988; 10: 509; Ambrojo et al. Am J Dermatopathol 1992; 14: 293; Sagol et al. East J Med 1999; 4: 37; Kwittken J. Cutis 2002; 69: 57; Kim et al. Yonsei Med J 2003; 44: 523] of BCC showing matrical differentiation have been reported. None have been reported arising on the background of immunosuppression. METHODS: A 58-year-old male cardiac transplant patient with a nodule on the dorsum of left hand was studied. It arose and enlarged rapidly within a few months, causing irritation and bleeding. The nodule was surgically excised and submitted for histopathologic evaluation. The sections were prepared by hematoxylin and eosin (H&E) method. RESULTS: The H&E-stained sections of the hand lesion revealed multiple nodular masses of basaloid follicular germinative cells. In some areas, there was peripheral palisading and stromal retraction artifact typical of classic BCC. In these areas, the tumor nodules were connected to the epidermis, whereas in others, it extended deep into the reticular dermis to the subcutaneous fat junction. Elsewhere, the majority of the tumor contained a population of shadow cells, similar to those in pilomatricoma, with basaloid-appearing matrical cells in the periphery. Trichohyaline granules were identified in the cytoplasm of many of the peripheral basaloid cells. These granules are one of the characteristic features of follicular matrix differentiation. Mitoses were rare. Areas of cystic degeneration were present throughout the tumor. There was no evidence of an infiltrating growth pattern, lymphovascular invasion, or sarcomatoid growth pattern. CONCLUSION: BCC with matrical differentiation is a distinct pathologic entity and a rare subtype of BCC featuring shadow and matrical cells, typically seen in pilomatricoma, a benign hair matrix neoplasm. This tumor has not yet been reported in an immunosuppressed transplant patient.     

Two Cases of Basal Cell Carcinoma Arising in Seborrheic Keratosis

The present study reports two cases of basal cell carcinoma arising in seborrheic keratosis. The first case is a seventy-three-year-old female who presented with a blackish nodule arising from a pigmented lesion on her chest. Histopathological analysis of the nodule and the pigmented lesion revealed a basal cell carcinoma with hair follicular differentiation and an acanthotic seborrheic keratosis, respectively. The second case is a seventy-year-old female with a blackish nodule arising from a pigmented lesion on her back. Histological analysis of the nodule revealed an atypical basaloid cell mass surrounded by a seborrheic keratosis lesion. In addition to the coexisting seborrheic keratosis with the basal cell carcinoma, a basaloid follicular hamartoma that showed muliple hamartomatous hair follicles or small cysts replaced by a branching cord or lace-like network of basaloid cells surrounded by fibrovascular stroma was identified. We concluded that both cases presented a rare combination of a seborrheic keratosis which underwent a malignant change to basal cell carcinoma. It appears that both basal cell carcinomas and seborrheic keratosis may derive from a similar source: pluripotential cells of either the epidermis or hair follicle epithelium.     

Rippled-pattern basal cell carcinoma

Basal cell carcinoma (BCC) is the most common malignant cutaneous neoplasm, however, there have been few studies on BCC with a "rippled pattern" so far. We reviewed the 650 BCC specimens from the archives of our institution, and only one example of BCC with a rippled pattern was found. We herein report the histopathological characteristics of this case. Within the lesion, which showed the typical histopathological features of nodular BCC, there was a noticeable area composed of 10-15 basaloid aggregations, which showed the rippled pattern. The rippled pattern was characterized by alternating bands of epithelial cords of spindle-shaped basaloid cells and mucinous spaces. Characteristically, around the rippled-pattern area, neoplastic aggregations with a mucinous reticulated or cystic pattern (pseudo-tubular structures), and many cord-like structures were seen. A review of the published work and the present case suggested that the histopathological characteristics of rippled-pattern BCC are: (i) a nodular type of BCC; (ii) considerably rare; (iii) have frequent intervention by mucinous spaces between the epithelial cords; and (iv) no apparent divergent differentiation with folliculosebaceous-apocrine lineage. The last three characteristics contrasted with those of the rippled-pattern sebaceoma/trichoblastoma. However, neoplastic germinative cells in rippled-pattern BCC may naturally form cord-like structures in a manner similar to rippled-pattern sebaceoma/trichoblastoma.     

Basaloid neoplasms in nevus sebaceus

BACKGROUND: Nevus sebaceus (NS) (organoider nevus) may frequently be associated with the development of a number of benign and malignant neoplasms among which basaloid neoplasms are the most common. Histopathologic criteria for diagnosis and classification of basaloid proliferations arising in NS are still debated. Most previous investigators have considered them to represent mainly basal cell carcinomas (BCCs). On the contrary, a number of recent authors have proposed that most basaloid neoplasms in NS exhibit predominantly morphologic features implying benignancy, thus representing trichoblastomas (TBs). In this study, we attempted to characterize better the histopathologic features of basaloid neoplasms in NS in a large series based on current morphologic criteria. METHODS: Three-hundred and sixteen cases of NS seen over 19 years were consecutively sampled and reviewed for basaloid neoplasms. Twenty-four cases of basaloid neoplasms in NS were identified and categorized based on current histopathologic criteria either as TB or BCC. For comparison of histopathologic features, 37 solitary TB were also studied. RESULTS: Following histopathologic analysis, 22 cases were categorized as TB (91.6%, 10 males, 12 females; mean age 40.8 years, range 19-78 years) and 2 cases as BCC (8.4%, 1 male, 1 female; 32 years and 40 years). Clinical features in both groups were generally similar. The lesions presented exclusively on the head and neck as skin colored to pigmented papules or nodules within NS (scalp in 19 TB cases and 1 BCC case; face in 2 TB cases and 1 BCC case; neck in 1 TB case). Histopathologically, TB in NS were characterized by smooth-bordered basaloid aggregations with either a nodular and/or a superficial pattern, abundant fibrous stroma with focal clefts within the stroma, and prominent features of limited follicular differentiation (rudimentary follicular germs in concert with papillae). In contrast, BCC in NS showed basaloid aggregations that vary markedly in size and shape, scant fibrous stroma, focal mucinous clefts between basaloid aggregations and surrounding stroma, and lack of prominent rudimentary follicular germs in concert with papillae. Remarkably, sections in a few cases of TB showed features occasionally found in BCCs but presently widely considered to be unspecific (e.g., ulceration, cystic degeneration, and focal clefts between basaloid aggregations and surrounding stroma). Two cases of TB in NS were associated with a sebaceoma and 1 case with a desmoplastic trichilemmoma. Follow-up data in 14 TB cases and 2 BCC cases (mean follow-up 28.8 months; range 1 to 160 months) revealed no local recurrences or distant metastases. CONCLUSION: Our study confirms that the vast majority of the basaloid neoplasms arising in NS show clear-cut morphologic criteria for TB, whereas only a few cases display histopathologic features consistent with BCC. In a minority of cases, basaloid neoplasms with overall morphologic features of TB may present problems in diagnosis when they exhibit a few histopathologic features traditionally associated with BCC or when they occur in combination with other adnexal neoplasms.     

Apocrine cystadenoma arising in a nevus sebaceus of Jadassohn

An increased incidence of benign and malignant adnexal tumors has been noted to occur within the nevus sebaceus of Jadassohn. We report a case of a 41-year-old white woman with a blue cyst on her scalp which had recently developed within a congenital "birthmark." Excision of the lesion revealed that the nodule was an apocrine cystadenoma within a nevus sebaceus of Jadassohn. The clinical features of nevus sebaceus with apocrine cystadenoma are discussed and the various tumors which may arise within the nevus sebaceus are reviewed.     

Muir-Torre syndrome: a case of this uncommon entity

A 69-year-old Hispanic woman presented for the evaluation of nodules on the head and back. In the past, she had been treated for basal cell carcinoma (BCC) of the face; the referring physician was concerned that the new lesions might also be BCC. The patient had an extensive past medical history. In addition to BCC, she had been treated for breast cancer, colon cancer, and cervical cancer prior to emigrating to the USA. Her colonic malignancy had been localized proximal to the splenic flexure. She also had a history of colonic polyps and distal colonic villous adenoma. She denied ever being treated with radiation. Further details of her medical history and cancer staging were not available. Her family history was significant for a sister with colon cancer and transitional cell carcinoma of the urinary bladder. In addition, she had a great aunt with oral cancer and a great uncle with lung cancer. Neither the patient or her relatives had any history of tobacco use. On physical examination, in addition to scars from a radical mastectomy and midline abdominal laparotomy, four skin lesions were noted: two on the scalp, one on the tragus, and one on the mid-back. The first lesion on the vertex of the scalp was a yellow-brown waxy papule measuring 0.6 x 0.5 cm. This lesion was similar to that on the mid-back, except in size. The lesion on the back measured 1.2 x 1.0 cm. The second lesion on the frontal scalp measured 0.8 x 0.6 cm and was red-brown with a pearly appearance and some central hyperkeratosis. The tragus lesion was similar in appearance to that on the frontal scalp. Shave biopsies of all lesions were obtained. The lesions on the scalp and mid-back revealed lobules of sebaceous cells in the dermis with a minority of surrounding basaloid cells, consistent with a diagnosis of sebaceous adenoma (Fig. 1). Although the lesion on the frontal scalp also showed sebaceous differentiation, there were a greater number of basaloid cells, some with hyperchromatic nuclei and mitotic figures; this was consistent with a diagnosis of sebaceous epithelioma (Fig. 2). The final lesion (tragus) was histologically consistent with a keratotic BCC. No further treatment was required for these benign sebaceous tumors, but their presence defined our patient's condition as Muir-Torre syndrome. Mohs' micrographic surgery was performed on the tragus BCC and the margins were tumor free in one stage. The patient returned 1 year later with a lesion anterior to the left axilla which was biopsied to rule out BCC (Fig. 3). Histologically, this lesion was also consistent with sebaceous epithelioma.     

皮脂腺痣并发毛母细胞瘤

报告1例皮脂腺痣并发毛母细胞瘤。患者女,39岁。出生即发现右侧耳周芝麻至粟粒大褐色丘疹。皮肤科检查:右侧耳前部可见条带状斑块,呈蜡样光泽,其上有结节,局部糜烂及结痂;右侧耳后部可见密集分布的蜡黄或棕褐色角化性丘疹或斑块,边界清楚。皮损组织病理检查:表皮突延伸,区域表皮长出多个原始的毛乳头样结构,周边细胞呈栅栏状排列;真皮层可见结节状的毛母细胞瘤以及大量皮脂腺结构,下方无毛囊。诊断:皮脂腺痣并发毛母细胞瘤。治疗:予手术切除。     

先天性限局型基底细胞样毛囊错构瘤

报告1例先天性局限型基底细胞样毛囊错构瘤.患儿于2个月龄时就诊,出生时发现右侧面部有淡红褐色、淡红色或肤色斑块、结节和皮赘样损害,无自觉症状.皮损直径数毫米至数厘米,分布于右侧颞部、外眦及颊部.患儿系统检查未见其他异常.家族中无类似病史.皮损组织病理检查符合基底细胞样毛囊错构瘤.     

Complex adnexal tumor of the primary epithelial germ with distinct patterns of superficial epithelioma with sebaceous differentiation, immature trichoepithelioma, and apocrine adenocarcinoma.

A 60-year-old man came for treatment of a sharply outlined erythematous plaque on the gluteal area (45 x 20 mm) of 20 years' duration. Eccentrically located on the plaque was a nodule, 20 mm in diameter. Histological study of the plaque showed a superficial platelike tumor with basaloid bland cytology and sebaceous gland differentiation. Histologic study of the nodule found an undifferentiated adenocarcinoma whose ductlike glandular structures opened to the skin surface and infiltrated the whole depth of the dermis. Study of other areas of the lesion detected two more neoplasms. A nodule of squamous cell carcinoma was found within the superficial band of the benign sebaceous tumor. The fourth neoplastic pattern consisted of epithelial islands composed of basaloid cells within a fibroblastic stroma. There was prominent palisading of epithelial cell nuclei at the periphery of the islands, which usually were surrounded by a sheath of mesenchymal cells. In this complex adnexal tumor of the primary epithelial germ, sebaceous and follicular differentiation both simulate neoplastic patterns recently described as separate entities: superficial epithelioma with sebaceous differentiation and immature trichoepithelioma. The undifferentiated adenocarcinoma may represent differentiation toward the third component of the germ, that is, the apocrine gland.     

Happle-Tinschert Syndrome: A Case Report of Unilateral Segmentally Arranged Basaloid Follicular Hamartoma with Scoliosis and Review of Literature

Happle-Tinschert syndrome is a rare disease characterized by unilateral, segmentally arranged basaloid follicular hamartoma (BFH) with osseous, dental, and cerebral anomalies. Although BFH has been demonstrated to be associated with mutations in the patched gene, the genetic basis for Happle-Tinschert syndrome is still unknown. We describe a case of Happle-Tinschert syndrome in a 26-year-old female. The patient presented with unilateral skin color change to brownish papules and atrophoderma following the development of Blaschko''s lines, plantar pitting, and nail dystrophy on the right side of the body. She also had scoliosis, hemihypotrophy, and dental anomalies. The skin lesions were histologically confirmed as BFHs. Next-generation sequencing of the patient''s genomic DNA obtained from a peripheral blood sample identified no pathogenic mutation. This case illustrates the characteristic clinical features of Happle-Tinschert syndrome. Thus far, 14 cases of Happle-Tinschert syndrome have been reported, and we report another case of this syndrome.     

CD10 expression in trichoepithelioma and basal cell carcinoma

BACKGROUND: Trichoepithelioma (TE) is a benign neoplasm that shares both clinical and histologic features with basal cell carcinoma (BCC). However, it is important to distinguish these neoplasms. Limited immunohistochemical stains are available to separate these two tumors. METHODS: CD10 protein immunohistochemistry was performed on paraffin-embedded biopsies of 13 TE and 23 BCC diagnosed by routine microscopy. Cases were analyzed for pattern of CD10 expression by tumor cells and surrounding stroma. RESULTS: Twelve of 13 (92%) TE showed positive stromal immunoreactivity. Of these, eight cases also demonstrated positivity of the papilla, and two also showed positivity of the basaloid cells. No TE demonstrated epithelial expression alone. On the other hand, expression of CD10 by basaloid cells was identified in 20 (87%) cases of BCC. Stromal positivity was also identified in three cases of BCC. Condensation of CD10-positive stromal cells around basaloid nests was statistically significant in differentiating TE from BCC (p < 0.0001). Conversely, CD10-positive basaloid cells were seen predominantly in BCC (p < 0.0001). CONCLUSIONS: This study demonstrates a statistically significant difference in CD10 staining pattern between TE and BCC. Thus, CD10 may be a useful adjunct marker in distinguishing these tumors.     

Familial Multiple Basaloid Follicular Hamartomas: A Report of Two Affected Sisters

Basaloid follicular hamartoma (BFH) is one of several benign skin tumors that may occur in multiple and solitary forms. While the histologic findings of BFH may be observed in a variety of clinical settings, familial multiple BFH represents a distinct clinical entity characterized by tiny flesh-colored papules scattered predominantly over the face. We present two sisters with this rare condition and review the clinical and histologic differential diagnosis of familial multiple BFH.     

Basaloid/follicular hyperplasia overlying connective tissue/mesenchymal hamartomas simulating basal cell carcinomas

BACKGROUND: Basaloid hyperplasia has been described overlying dermatofibromas as well as in the epidermis overlying nevus sebaceus. Although the morphology of these areas may resemble that of basal cell carcinoma (BCC), in the majority of cases aggressive behavior of the proliferation is not seen. In fact, the basaloid proliferation often shows follicular differentiation and may be stimulated and maintained by its relationship with the underlying stromal cells. OBJECTIVE: We wanted to determine whether immunohistochemical staining for antibodies, which may suggest differences in pathogenesis, were different in basaloid hyperplasia overlying connective tissue/mesenchymal hamartomas and BCC. METHODS: We report 3 cases of connective tissue/mesenchymal hamartomas with overlying basaloid hyperplasia, in which the areas of the basaloid proliferation showed follicular differentiation. Immunohistochemical stains included Ber-EP4, PCNA, Ki-67, Bcl-2, p53, SM-Actin, CD31, factor XIIIa, KP-1, and CD34. RESULTS: There was a diffuse positive reaction for Ber-EP4 in all specimens and there was increased nuclear staining for PCNA and Ki-67. There was focal cytoplasmic staining for Bcl-2 in the areas of basaloid hyperplasia. Immunohistochemical staining for p53 showed only scattered positive cells except in a small focus in the areas of basaloid hyperplasia. The connective tissue component of all lesions showed diffuse staining for CD34 surrounding areas of basaloid hyperplasia in the mesenchymal component as well as in abundant S-100(+) nerves. CONCLUSION: The areas of basaloid hyperplasia in these hamartomas exhibited an immature phenotype similar to that seen in both BCCs and follicular tumors; however, the patterns of proliferation markers, p53, Bcl-2, and the surrounding stromal cell markers were similar to those of benign follicular tumors. Thus the staining pattern for this group of antibodies suggests that areas of basaloid hyperplasia are not BCC.     

Squamous cell carcinoma of the skin: dual differentiations to rare basosquamous and spindle cell variants

Basosquamous carcinoma (BSC) is defined as a tumor containing the areas of both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) with a transition zone linking the two. Spindle cell squamous carcinoma (SCSC) may have a variable component of conventional SCC and spindle cells. We present a case of an 89-year-old woman with an eruption on the scalp for several decades. Grossly, the lesion measured 8.5 x 6.0 x 1.8 cm and consisted of a gray-white and focally black tumor. Microscopically, a non-ulcerated upper part of the tumor consisted of large polygonal squamoid cells with occasional keratinization (SCC), trabecular growth of basaloid cells with peripheral palisading (BCC), and an area in which both the components were intermingled. The rest of the tumor was a myxoid area with elongated fusiform spindle cells, which appeared to arise from conventional SCC. Immunohistochemically, the tumor cells in the SCSC (both conventional and spindle cell) area co-expressed CAM5.2, and vimentin. Ber-EP4 was positive in the BCC area with the transition zone of SCC and BCC showing diminished staining. Epithelial membrane antigen was focally positive in the conventional SCC area. To our knowledge, this is the first case report of SCC of the skin that has dual differentiations to BSC and SCSC.     

Keloidal basal cell carcinoma after radiation therapy

We report a case of keloidal basal cell carcinoma (BCC) that developed after radiation therapy. A 67-year-old Japanese man had received radiation therapy of an unknown amount for three years for the treatment of right cervical lymph node tuberculosis at the age of 7. Within the area of chronic radiation dermatitis, on the right preauricular region, he presented with a skin-colored to erythematous, firm nodule. Histopathologically, this nodule showed features of keloidal BCC. The stroma characteristically demonstrated the prominent, keloidal, thickened collagen bundles standing out against the surrounding actinic-damaged dermis, and well-circumscribed, keloidal collagen bundles that proliferated in a nodular form almost corresponding to a clinically firm, nodular lesion. There was no radiation fibrosis around the keloidal BCC. We discuss the differences between keloidal BCC and morpheiform BCC, and consider keloidal BCC to be a rare variant of BCC from a clinico- pathological basis.