Carcinoid-Like/Labyrinthine Pattern in Sebaceous Neoplasms Represents a Sebaceous Mantle Phenotype: Immunohistochemical Analysis of Aberrant Vimentin Expression and Cytokeratin 20-Positive Merkel Cell Distribution.

This study investigated the nature of carcinoid-like, labyrinthine, rippled, and conventional cell arrangements in sebaceous neoplasms, focusing on vimentin expression and Merkel cell distribution in sebaceous neoplasms relative to these findings in normal sebaceous units and other sebaceous conditions. Immunohistochemistry for vimentin and cytokeratin 20 (CK20) was evaluated in carcinoid-like (n = 2), labyrinthine (n = 4), rippled (n = 3), and conventional (n = 6) sebaceomas; sebaceous mantle hyperplasia (n = 1); steatocystomas (n = 5); fibrofolliculomas (n = 4); sebaceous mantleoma (n = 1); sebaceous gland hyperplasias (n = 4); sebaceous adenomas (n = 4); and sebaceous carcinomas (n = 4) as well as normal skin tissue. The sebaceous mantle and its hamartoma (fibrofolliculoma) showed weak positivity for vimentin in the basal layer of the epithelial component and contained a few CK20-positive Merkel cells within the epithelial component, whereas mature sebaceous lobules were negative for vimentin and did not contain any Merkel cells. All sebaceomas with carcinoid-like or labyrinthine pattern highly expressed vimentin. CK20-positive Merkel cells were distributed with varying numbers in carcinoid-like pattern (2/2) and labyrinthine pattern (3/4) sebaceomas, sebaceous mantle hyperplasia (1/1), steatocystomas (3/5), fibrofolliculomas (3/4), and sebaceous mantleoma (1/1). Vimentin expression and Merkel cell distribution were observed in normal sebaceous mantles and sebaceous mantle-associated lesions, which could be evidence of a sebaceous mantle nature in the limited setting of sebaceous lesions. Furthermore, carcinoid-like/labyrinthine pattern sebaceomas also showed vimentin immunoreactivity and contained Merkel cells. Therefore, carcinoid-like/labyrinthine pattern of cell arrangement in sebaceous neoplasms may represent a morphological phenotype of sebaceous mantles.

Low-Grade Neuroendocrine Carcinoma of the Skin (Primary Cutaneous Carcinoid Tumor) as a Distinctive Entity of Cutaneous Neuroendocrine Tumors: A Clinicopathologic Study of 3 Cases With Literature Review.

There is scarcity of information on primary cutaneous low-grade neoplasms commonly known as carcinoid tumors, owing to their rarity. The authors present 3 cases that were named "low-grade neuroendocrine carcinoma of the skin" (LGNECS). These occurred in the dermis and subcutis of the anterior chest or the inguinal region in the elderly. Histologically, the tumors showed infiltrating proliferation of nests of various sizes, with low-grade neuroendocrine cytologic features but without mucin production. All cases exhibited varying degrees of intraductal tumor components. On immunohistochemical examination, these tumors expressed estrogen receptor alpha, progesterone receptor, androgen receptor, gross cystic disease fluid protein 15, mammaglobin, and GATA3 as well as neuroendocrine markers. Although a literature review revealed 8 additional possible cases with no evidence of other diseases, it was difficult to determine if these were true cases of LGNECS, because of the limited information available. Based on its characteristic histologic features and immunoprofile, it can be proposed designating LGNECS as a distinct entity among cutaneous neuroendocrine tumors. Otherwise, such tumors could be misdiagnosed as mammary carcinomas (particularly when involving the skin of the breast) or as metastatic visceral neuroendocrine tumors of the skin.

CD117 (KIT) is a useful immunohistochemical marker for differentiating porocarcinoma from squamous cell carcinoma.

BACKGROUND: Distinguishing porocarcinoma from squamous cell carcinoma (SCC) is clinically significant but can pose a diagnostic dilemma. The present study sought to confirm the diagnostic utility of CD117 immunohistochemistry in distinguishing porocarcinoma from SCC and to examine histologic, carcinoembryonic antigen (CEA) immunohistochemical and CA19-9 immunohistochemical differences between these tumors. METHODS: Immunostaining with anti-CD117, anti-CEA and anti-CA19-9 antibodies was performed for 22 porocarcinomas and 31 SCCs. The extent of CD117, CEA and CA19-9 staining was classified as negative (<1%), rarely positive (1-4%), focally positive (5-29%) or diffusely positive (30-100%). CD117 staining intensity was semi-quantitatively graded as weak, moderate or strong. RESULTS: All (100%) porocarcinomas were positive for CD117, with mainly focal (8/22) or diffuse (11/22) and moderate (9/22) to strong (8/22) staining. In contrast, only 6 of 31 SCCs (19.4%) expressed CD117 focally, and this expression was limited to the basal layer of the tumor in four cases. CEA immunostaining highlighted the lumina of all 22 porocarcinomas; however, CEA expression was not significantly different between porocarcinomas and SCCs (100 vs. 71.0%, respectively). CA19-9 was not expressed in the lumina of 5 of 22 porocarcinomas. CONCLUSIONS: Along with CEA, CD117 immunohistochemistry could be helpful in distinguishing porocarcinomas from SCCs.

Spiradenocarcinoma in Preexisting Spiradenoma With a Large In Situ Adenocarcinoma Component.

Spiradenocarcinoma is a very rare malignant tumor. In situ adenocarcinoma has recently been observed and defined by the preservation of a peripheral myoepithelial cell layer. The pathway for this phenomenon has been hypothesized to involve a sequence of adenomatous changes followed by atypical adenomatous changes, adenocarcinoma in situ, and invasive adenocarcinoma. However, there are no clearly defined morphological distinctions between atypical adenomatous changes and adenocarcinoma in situ. The authors present a case of spiradenocarcinoma in a preexisting spiradenoma in the left inguinal area of a 71-year-old woman. Adenomatous changes, atypical adenomatous changes, adenocarcinoma in situ, and invasive adenocarcinoma were found within the same lesion. The majority of the malignant component was an in situ adenocarcinoma. Although a loss of the myoepithelial cell layer and coalescing, irregular, glandular nests were present in several discrete foci, this case did not show infiltrative growth beyond the fibrous connective tissue. The authors speculate that this case represents a very early invasive spiradenocarcinoma lesion. We present this case to discuss the histological and/or immunohistochemical criteria of atypical adenomatous changes and to discuss the optimal treatment in cases with a disparity between the preservation of the whole architecture and the loss of the myoepithelial cell layer, which may be associated with favorable biological behavior.

A clinicopathologic and immunohistochemical study of 7 cases of sclerosing perineurioma.

Sclerosing perineurioma is a relatively rare tumor that has remained widely unknown since first reported by Fetsch in 1997. To our knowledge, no large or small series of claudin-1 in sclerosing perineurioma has been confirmed to date. We collected 7 new cases of sclerosing perineurioma. Six patients were female, and 1 was male. The patients' age ranged from 15 to 58 years (mean, 36.6 years; median, 42.0 years). The primary reason for consultation at the outpatient clinics was a slowly enlarging mass. The preoperative durations were available for 4 of the 7 cases and ranged from 2 to 7 years. Six tumors were located in the fingers, and the other tumor was found in the palm. The sizes ranged from 4 to 12 mm in diameter (mean, 6.7 mm; median, 6.0 mm). Microscopically, all tumors were nodular lesions, with sclerotic stroma involving reticular dermis primarily consisting of small oval epithelioid cells and plump spindle cells, scattered and arranged in corded, trabecular, reticular, and/or whorled growth patterns. The neoplastic cells were immunoreactive for epithelial membrane antigen (7 of 7) and glucose transporter 1 (7 of 7). The periodic acid-Schiff reaction and positive immunostaining for type IV collagen were observed directly adjacent to the lesional cells in all cases (6 of 6). Claudin-1 immunostaining was positive in all 7 cases, suggesting that claudin-1 may serve as a helpful diagnostic marker for sclerosing perineurioma.

Cytokeratin expression patterns in multiple infundibulocystic basal cell carcinoma.

Infundibulocystic basal cell carcinoma (IBCC) is a variant of basal cell carcinoma. Sporadic cases usually represent a solitary tumor and multiple IBCC is rare. There have been no reports in which the tumor differentiation is characterized immunohistochemically. We report a case of multiple IBCC which developed on a patient's scalp by performing histopathological and immunohistochemical examinations, using monoclonal antibodies against cytokeratins (CKs). A 76-year-old female had noticed multiple small papules on her scalp. She noticed that the tumors were growing when she underwent systemic chemotherapy for metastatic lung cancer. Routine histopathological specimens from skin biopsies revealed findings typical of IBCC. The tumor cells expressed CK14 and CK17. However, CK1 and CK10 were expressed only in a few cells in the inner area of the tumors. The present case is unique in two points. First, multiple tumors developed on the patient's scalp during the systemic chemotherapy for the lung cancer. Second, the tumor showed CK expression patterns characteristic to infundibular and trichilemmal epithelia.

Sebaceous carcinoma: an immunohistochemical reappraisal.

The rates of distant metastases and tumor death in sebaceous carcinoma (SC) have been reported to be higher than those of other cutaneous carcinomas, such as squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), regardless of whether they occur in ocular or extraocular regions. Therefore, strict differentiation of SC from SCC and BCC is required. In this article, we report immunohistochemical findings of SC and compare these data to those of SCC, BCC, and sebaceoma. An immunohistochemical study was performed using 7 antibodies [anti-carcinoembryonic antigen (CEA), anti-epithelial membrane antigen (EMA), anti-CA15-3, anti-CA19-9, anti-androgen receptor (AR), anti-epithelial antigen (Ber-EP4), and anti-adipophilin (ADP)] on 35 cases of SC (16 cases in ocular and 19 cases in extraocular regions) and 10 cases of each SCC (5 cases in ocular and 5 cases in extraocular regions), BCC (5 cases in ocular and 5 cases in extraocular regions), and sebaceoma (no cases arose on the eyelids). In summary, the typical immunophenotypes of SC were EMA+, CA15-3+, AR+, Ber-EP4-, and ADP+; those of sebaceoma were CEA-, EMA+, Ber-EP4-, and ADP+; those of SCC were CEA-, EMA+, CA19-9-, AR-, Ber-EP4-, and ADP-; and those of BCC were CEA-, EMA-, CA15-3-, Ber-EP4+, and ADP-. Other antibody tests for each neoplasm were positive in about half of the cases. The detection of AR and ADP was useful for differentiating SC from SCC, whereas the determination of EMA, CA15-3, Ber-EP4, and ADP was valuable in differentiating SC from BCC.

Reassessment of histopathology and dermoscopy findings in 145 Japanese cases of melanocytic nevus of the sole: toward a pathological diagnosis of early-stage malignant melanoma in situ.

Recently, dermoscopic visualization has been improved, allowing for the identification of malignant melanoma (MM) of the sole in situ. When the parallel ridge pattern is evident on dermoscopy, the proliferation of solitarily arranged melanocytes in the crista profunda intermedia should be examined histologically, since this may be a clue to the early diagnosis of MM in situ. We reviewed 145 Japanese cases of melanocytic nevus on the sole, and investigated several useful histological features for the diagnosis of MM in situ using a recent proposal as well as several standard histological criteria of MM in situ. Five cases were considered to be an early-stage MM in situ out of 145 cases previously diagnosed as melanocytic nevi of the sole. These cases showed several specific features, including solitarily arranged melanocytes or melanocyte nests comprising fewer than four cells. Our findings indicate that early-stage MM of the sole in situ can be diagnosed by using new dermoscopy-related histological findings. They are (i) irregular distribution of solitary melanocytes at the crista profunda intermedia with or without small nests (up to three melanocytes) on the slope of rete ridges; and (ii) larger melanocytes with a halo around the nucleus.

A clinicopathologic study of folliculosebaceous cystic hamartoma.

Folliculosebaceous cystic hamartoma (FSCH) is a distinctive cutaneous hamartoma of follicular, sebaceous, and mesenchymal components. Only 70 cases of FSCH have been reported in the literature since the original report of 5 cases in 1991. There has been little information reported about the clinicopathologic characteristics of FSCH. We summarize the clinicopathologic features of 153 cases of FSCH that were diagnosed histopathologically at Sapporo Institute for Dermatopathology. The 153 cases of FSCH comprised 92 male and 61 female patients. The typical clinical presentation of FSCH revealed solitary and skin-colored, protruding papules or nodules measuring several millimeters in diameter on the face, especially on the nose, of middle-aged or older persons. These cases fulfilled the common denominators for the histopathologic diagnosis of FSCH as Kimura et al reported. Seven of 153 cases (4.6%) were accompanied by distinctive features of Miescher-type melanocytic nevi. All 7 cases showed lesions on face, especially on or around the nose. We consider that Miescher-type melanocytic nevi play a significant role in the pathogenesis of FSCH, at least in some cases.

A revaluation of trichofolliculoma: the histopathological and immunohistochemical features.

Few investigations on the histopathology of trichofolliculoma (TF) have so far included an immunohistochemical study. To seek new insight into TF with a revaluation of the histopathological features and an investigation of the immunohistochemical profile, 14 TFs were revaluated for the histopathology and the immunohistochemical profile of various cytokeratins (CKs), hair follicle stem cell markers, and others. The CK15 expression was upregulated in the basal cells from the primary cystic structures beyond to secondary follicles without expression of CK19. CK16 and CK17 were positive in the suprabasal cells of the primary cystic structures and the immature secondary hair follicles. No exact isthmus/bulge region was seen in the anagen secondary hair follicles, and newly developed (tertiary) hair follicles arose randomly from the involuting secondary follicles. Ber EP4 expression was generally weakened in the secondary or tertiary hair germ-like structures. The size of secondary hair follicles varied from vellus hair follicles to terminal hair follicles, even though no lesions located on the regions where the terminal hairs develop were included in this study. S-100 protein-positive wavy spindle cells were accidentally found in the surrounding connective tissue of the secondary follicles in 2 TF lesions. TFs were characterized by the proliferation of abnormal CK15-positive hair follicle stem cells, which basically differentiated toward the outer root sheath and attempting to make hair but losing the proper differentiation. The control of the size of the anagen hair follicles and the regular hair cycle were also disordered.

A revaluation of folliculosebaceous cystic hamartoma: the histopathological and immunohistochemical features.

The histogenesis of folliculosebaceous cystic hamartoma (FSCH), including the origin of the frequently associated adipocytes and other mesenchymal components, remains unclear. There are controversial problems regarding FSCH, such as the relationship between FSCH and trichofolliculoma (TF), and the exact concept of sebaceous TF. Fourteen FSCHs and 1 sebaceous TF were revaluated for the histopathology and studied for immunohistochemical profile of various cytokeratins, hair follicular stem cell markers, and others. The nestin expression was partly upregulated in the sebaceous duct structures and the proliferating spindle cells in the surrounding connective tissue in some lesions. S-100 protein staining clarified the presence of lipogenesis in these nestin-expressed lesions, and the nestin-positive spindle cells were also seen around the immature adipocytes. Some FSCHs showed the focal follicular differentiation, where no signs of catagen or telogen stage were seen. One peculiar case showed both FSCH and TF features equally. The possibility that the adipocytes and other mesenchymal components in FSCHs originated from the nestin-positive multipotent stem cells was suggested. It is not convincing that FSCH and TF represent a chronological change in the spectrum of the same condition. Each FSCH and TF is therefore considered to be a distinctive entity. They may develop under a similar pathogenesis differing from each other in the direction of fundamental differentiation. In contrast to the TF lesions, the unusual upregulation of nestin expression is occasionally seen in FSCH lesions, including their stromas, which may thus result in the production of various kinds of mesenchymal components in FSCHs.

Pilomatricoma can differentiate not only towards hair matrix and hair cortex, but also follicular infundibulum, outer root sheath and hair bulge.

Pilomatricoma is believed to differentiate towards the hair matrix and hair cortex. To elucidate the origin of differentiation in pilomatricoma, we studied the expression of epithelial keratin (K) and filaggrin (filament aggregating protein) in pilomatricoma. An immunohistochemical study has been made of 53 cases of pilomatricoma using 10 monospecific anti-keratin antibodies and anti-filaggrin antibody. Basophilic cells, transitional cells and shadow cells did not react with epithelial keratins and filaggrin antibodies as well as hair matrix and hair cortex. Instead, infundibular-type epithelium was positive for K1, K10 and filaggrin. Epithelium showing trichilemmal keratinization was positive for K14 and K16. The hair bulge-like structure was positive for K19. The differentiation of pilomatricoma is diversified, and is heterogeneous in epithelial keratin and filaggrin expression. Our results for keratin and filaggrin expression suggested that pilomatricoma can differentiate not only towards hair matrix and hair cortex, but also follicular infundibulum, outer root sheath and hair bulge.

Fibrofolliculoma/trichodiscoma and fibrous papule (perifollicular fibroma/angiofibroma): a revaluation of the histopathological and immunohistochemical features.

BACKGROUND: The multiple facial lesions of fibrofolliculoma (FF)/trichodiscoma (TD) and those of fibrous papule (FP; perifollicular fibroma/angiofibroma, AF) are characteristic of Birt-Hogg-Dubé (BHD) syndrome and tuberous sclerosis, respectively. However, there was a recently reported case of BHD syndrome with multiple facial FP lesions and a case of tuberous sclerosis, in which one FF lesion was included among the multiple facial FPs. METHODS: The histopathological and immunohistochemical features of FF/TD and FP lesions were revaluated to study the relationship between the two. This investigation evaluated 20 FF/TD lesions including two cases of BHD syndrome and 35 FP lesions including three cases of tuberous sclerosis. RESULTS: There are common histopathological features in the two lesions, such as the follicular and perifollicular elements, an angiofibromatous element and stellate fibrocytes. The similar immunohistochemical features between the two lesions included the expression patterns of CD34, factor XIIIa, nestin and c-kit in the stromal cells as well as abnormal CK15 expression in the hair follicles. CONCLUSIONS: Both FF/TD and FP are hamartomas composed of perifollicular or interfollicular connective tissue and a hair follicular epithelial component, which may be caused by an abnormal functioning of the hair follicle bulge cells.

Rippled-pattern sebaceoma: a clinicopathological study.

We summarized the clinicopathological data of rippled-pattern sebaceoma diagnosed at Sapporo Institute for Dermatopathology and compared it with those of sebaceoma without rippled pattern. Eighty cases of sebaceoma, comprising 37 male and 43 female patients with a mean age at resection of 62.9 +/- 17.0 years, were reviewed. The lesions were located most frequently on the face (45.0%). Twenty-one (26.3%) of 80 cases of sebaceoma exhibited a rippled pattern. Rippled-pattern sebaceoma arose predominantly in males and most frequently on the scalp, whereas sebaceoma without rippled pattern occurred more frequently in females and on the face. Histopathologically, sebaceoma without rippled pattern frequently associated with other neoplastic lesions including sebaceous nevus, seborrheic keratosis, and trichoblastoma on the same lesion; however, there were no associated lesions in rippled-pattern sebaceoma.

Histopathologic findings in Unna's nevus suggest it is a tardive congenital nevus.

According to A. Bernard Ackerman's clinical histopathologic classification of nevi, the essential histopathologic finding of an Unna's nevus is localization of melanocytic nevus cells to a markedly thickened papillary dermis of an exophytic lesion. In this study, we examined 94 completely resected Unna's nevi in which several sections of the same lesion could be examined. We examined that melanocytic nevus cells were not just localized to the exophytic portion but were also commonly distributed below it (81 lesions, 86.2%). Melanocytic nevus cells were found in a periadnexal distribution in most of the lesions in which they extended below the exophytic part and were most frequently noted around hair follicles (60 lesions, 63.8%), then around eccrine ducts (43 lesions, 45.7%), and least frequently around sebaceous glands or ducts (36 lesions, 38.3%). Nests of melanocytic nevus cells were present in follicular epithelium in 7 lesions, sebaceous ducts in 1 lesion, and eccrine ducts in 1 lesion. Moreover, type A nevus cells containing melanin granules were observed in 16 lesions (17.0%) when they were distributed around hair follicles, in 8 lesions (8.5%) when distributed around sebaceous glands or ducts, and in 1 lesion (1.1%) when distributed around eccrine ducts. Although Unna's nevus is clinically an acquired nevus, it has many histopathologic characteristics of a congenital melanocytic nevus and is therefore likely a tardive congenital lesion.

Two cases of seborrheic keratosis with basal clear cells.

Seborrheic keratosis with basal clear cells (SKBCC) is an extremely rare histopathological variant of seborrheic keratosis that has histological similarities to melanoma in situ. We herein report two cases of SKBCC and provide the first description of the dermoscopic features of this condition, in addition to the histopathological findings. Both of the two lesions showed typical histological architectures of seborrheic keratosis with rows or focal clusters of monomorphic clear cells with abundant pale cytoplasm and small round nucleus in the basal layer. Immunohistochemical examination revealed that most clear cells were positive for high molecular weight cytokeratin (34ßE12) in a peripheral pattern but were negative tor Melan-A. Dermoscopy revealed typical features of ordinary seborrheic keratosis, while unfortunately did not reflect the presence of basal clear cells.

Clinicopathological analysis of 384 cases of poroid neoplasms including 98 cases of apocrine type cases.

We examined 384 cases of poroid neoplasms. Most cases (n = 279, 72.7%) exhibited the features of only one subtype. One hundred and ninety-eight cases (51.6%) showed only the features of poroma (P), 20 (5.2%) hidroacanthoma simplex (HS), five (1.3%) dermal duct tumor (D) and 56 (14.6%) hidradenoma (HA). Composite tumors of those four subtypes were observed in 105 cases (27.3%). In the trunk and lower extremities, lesions with the features of P were observed at higher rates than other sites. Those of HS and D were more frequently observed in the lower extremities. Those of HA were seen at higher rates in the scalp, face, neck and genitalia. Ninety-eight cases (25.5%) showed decapitation secretion and diagnosed as apocrine type lesion. Apocrine type lesions were frequently observed in the lesions on the genitalia (40.0%), scalp (31.8%) and trunk (31.1%), whereas at lower rates in those on the neck (21.4%) and lower extremities (24.0%). In apocrine type cases, the lesions were located more frequently on the scalp and trunk than non-apocrine type, whereas were less frequent on extremities. The rate of apocrine type lesions in the cases with only one subtype (19.7%) was lower than that of those with composite tumors (41.0%). In the apocrine type (43.9%), composite tumors are more frequent than in the non-apocrine type (21.7%). In D (40.8%) and HA (32.3%), apocrine type lesions were more frequently observed than other subtypes. In conclusion, it should be noted that a quarter of poroid neoplasms are composite tumors and/or show apocrine differentiation.

Localized Subcutaneous Insulin-Derived Amyloidosis Excised after Evaluation Using Ultrasonography in a Patient with Type 2 Diabetes Mellitus.

A 62-year-old man with type 2 diabetes mellitus, who had been on insulin therapy for the past 20 years, was found to have subcutaneous mass formation in the abdomen during a workup of worsened glycemic control. Because of suspected amyloid deposition, he was advised to avoid injections to the mass, which led to improvement of glycemic control. However, he strongly requested mass excision and was hospitalized. After evaluation using ultrasonography and computed tomography, a total mass excision was performed, and a diagnosis of insulin-derived amyloidosis was made. Comparison of the ultrasonographic and histopathological findings demonstrated that the location of the amyloid deposition nearly corresponded to the hypoechoic region. This case highlights that ultrasonography, which is a noninvasive imaging modality, can be useful for detection of insulin-derived amyloidosis.