Collision Tumor Associated with Sarcomatoid Eccrine Porocarcinoma and Basal Cell Carcinoma

A ‘collision’ tumor refers to the existence of two different neoplasms within the same tumor. Sometimes, the term ‘biphasic tumor’ is also used. However, a ‘collision’ tumor is defined as the occurrence of two neoplasms within proximity of each other yet maintaining distinctly defined, separate boundaries. In contrast, a ‘biphasic’ tumor demonstrates two or more phenotypically distinct neoplastic cell populations merging within the same space. Here, we report a case of collision tumor associated with sarcomatoid eccrine porocarcinoma and basal cell carcinoma arising in a 57-year-old male patient.     

Bowen's disease with invasive adnexal carcinoma: the pluripotential nature of Bowen's disease cells

Bowen's disease rarely exhibits multiple combinations of premalignant and/or malignant skin lesions. Bowen's disease with invasive adnexal carcinoma was originally described by Kao, but is not well recognized by clinicians due to its rarity and lack of specific clinical features of this condition. Herein, we describe three unusual cases of Bowen's disease with invasive adnexal carcinoma. The two distinct neoplastic areas exhibited continuity both clinically and histologically. The plaque lesions possessed clinical features typical of Bowen's disease. In cases 1 and 3, we confirmed the adnexal tumor within tumors of Bowen's disease, the diagnosis of which is eccrine porocarcinoma. The tumor in case 2 was characteristic to trichilemmal carcinoma. Immunohistochemically, the tumor cells of Bowen's disease and the adnexal carcinoma differed in antigenicities. The present cases support a notion that Bowen's disease maintains a pluripotential nature.     

A Case of Multiple Eccrine Porocarcinoma with Stepping-Stone Distribution on the Foot

An 89-year-old woman had three tumors of several years' duration in a stepping-stone distribution on the dorsum of her right foot. The two larger ones were diagnosed histologically as eccrine porocarcinomas, and the smallest of the three shared many clinical similarities with them. Eccrine porocarcinoma is a rare malignant tumor. We describe this peculiar case in which three tumors developed in the same region and discuss how they might have occurred. It is most likely that the three tumors of this case originated from nevoid tumors, and that the individual lesions exhibited malignant changes.     

Recurrent primary cutaneous mucinous carcinoma with neuroendocrine differentiation: case report and review of the literature

We report the case of a 60‐year‐old woman presenting with primary cutaneous mucinous carcinoma (PCMC) with neuroendocrine differentiation, revealed by neuroendocrine tumor lymph node metastasis 7 years before identification of the skin tumor. Only five cases of PCMC with neuroendocrine differentiation have been reported to date. The frequency of this neuroendocrine component may be underestimated, as it can require immunohistochemistry for identification, rather than being obvious on initial histopathologic examination. In the case presented here, the prominent neuroendocrine component displayed the morphological features of a well‐differentiated neuroendocrine tumor with expression of common neuroendocrine markers, strong expression of estrogen and progesterone receptors and low Ki67 proliferation index (5%). This case shows that not all primary cutaneous neuroendocrine carcinomas are Merkel cell carcinomas (MCCs). In addition to rare primary cutaneous carcinoid tumors, the diagnosis of PCMC with neuroendocrine differentiation must be considered, particularly when confronted by a mucinous tumor or lymph node metastases of neuroendocrine carcinoma of unknown origin. On the basis of this case, identification of a neuroendocrine component in a PCMC might be an adverse prognostic indicator of recurrence or of lymph node metastasis and should support wider excision margins of the tumor.     

Hidradenocarcinoma showing prominent mucinous and squamous differentiation and associated pagetoid cells

Herein, we report a 63‐year‐old man presenting with hidradenocarcinoma showing prominent mucinous and squamous differentiation on his back. The tumor was dermal‐based, solid and cystic. Tumor cells with squamous differentiation and with keratin pearl formation were identified predominantly in the superficial dermis, and mucinous cells were identified principally in the cystic lesion in the deep dermis. Interestingly, the additional feature of pagetoid cells was identified in the overlying epidermis. Both the mucinous cells in hidradenocarcinoma and pagetoid cells had intracytoplasmic mucin; however, they had different histopathologic findings and immunophenotypes. Mucinous cells in hidradenocarcinoma had small nuclei and abundant intracytoplasmic mucin presenting goblet cells with low rate of positive immunostaining for p53 and Ki67. In contrast, pagetoid cells had larger nuclei with less intracytoplasmic mucin. Both p53‐ and Ki67‐positive cells were increased in pagetoid cells. Additionally, mucinous cells in hidradenocarcinoma were MUC1(+)/MUC2(?)/MUC5AC(+)/MUC6(+), but pagetoid cells were MUC1(+; focal)/MUC2(?)/MUC5AC(?)/MUC6(+; focal). The derivation of pagetoid cells is unclear; however, the localized small region of pagetoid cells over the hidradenocarcinoma in the present case may suggest a common histogenesis of these two malignant neoplasms.     

Bowen disease with invasive mucin‐secreting sweat gland differentiation: Report of a case and review of the literature

Bowen disease (BD) with divergent adnexal differentiation is a rare composite cutaneous tumor featuring different phenotypic elements. Sebaceous, poroid and trichilemmal invasive components have been described in this setting and very infrequent reports of mucinous glandular differentiation are extant. Clinically, these tumors are not sufficiently distinctive to enable recognition without histopathological evaluation. From a microscopic perspective, care must be taken to exclude a collision tumor as well as other combined cutaneous neoplasms featuring squamous and glandular differentiation. Direct continuity between the two epithelial phenotypes helps to establish the correct diagnosis and generates interesting speculation about the pathogenesis of these and other epithelial skin tumors. We describe a case of BD in continuity with an invasive adenocarcinoma exhibiting mucinous sweat gland differentiation on the face of an elderly man. Details of the case are outlined with the objective of adding to a scant literature on this topic.     

Mucinous hidradenoma in a child—A case report and review of the literature

Hidradenomas are benign tumors of the sweat glands that are rarely reported in childhood. The presence of mucinous change in hidradenomas, which consists of variable numbers of mucin‐rich goblet cells, is occasionally observed in some adult clinical practices. However, it has not been previously reported in the pediatric population. Herein, we present a unique case of a mucinous hidradenoma presenting on the thigh of a 3‐year‐old boy. The clinical presentation and histological features of the case, along with a literature review of published case reports of pediatric hidradenomas are described. We present this case in order to highlight this variant of hidradenoma and to reinforce its inclusion in the differential diagnosis of neoplasms/conditions of childhood with mucinous differentiation.     

Eccrine Porocarcinoma: A Multicenter Retrospective Study with Review of the Literatures Reported in Korea

BackgroundEccrine porocarcinoma (EPC) is a rare malignant cutaneous adnexal tumor. Other than several scattered case reports, no comprehensive review on EPC has been conducted in Korea.ObjectiveTo clinicopathologically review all EPC cases from our institutions as well as those reported in Korea.MethodsMedical records and histopathological slides of EPC cases in the skin biopsy registries of our institutions were retrospectively reviewed. Additionally, EPC cases reported in Korea before June 2019 were retrieved by searching the PubMed, KoMCI, KoreaMed, and KMbase databases.ResultsNine EPC cases from our institutions were included in the study. In addition, 27 reports of 28 patients with EPC were reported in Korea. A total of 37 patients with EPC were identified, consisting of 19 males (male:female ratio, 1.06:1; mean age at diagnosis, 65.6 years). The most common site of primary tumor was the head and neck (29.7%). Wide excision was the most common (78.4%) treatment method. Initial metastasis work-up imaging studies were performed in 18 patients (48.6%), and metastasis was confirmed in eight patients (21.6%).ConclusionEPC is a rare cutaneous carcinoma in Korea. EPC usually affects elderly patients, with no sexual predilection. Due to possible metastasis, careful diagnosis and appropriate metastasis work-ups are warranted in EPC.     

Cutaneous mixed tumor with prominent pilomatricomal differentiation

Cutaneous mixed tumors show a wide range of differentiation and metaplastic changes in their components. However, pilomatricomal differentiation is a rare phenomenon and, when present, is usually only focal. We report a case of a 59-year-old male who presented with a large tumor in the scalp. Histopathologic examination revealed an apocrine mixed tumor with prominent pilomatricomal differentiation.     

Primary cutaneous mucinous carcinoma: report of two cases treated with Mohs' micrographic surgery

We present a 72-year-old woman who presented with a slowly enlarging, asymptomatic, cystic nodule on the right eyebrow, and a 66-year-old woman who had a reddish, nodular lesion on the left lower eyelid. Incisional biopsy from the two neoplasms showed dermal epithelial cell islands embedded in mucin pools. Tumour cells stained positive for cytokeratin 7, oestrogen and progesterone receptors, and negative for vimentin and S-100 protein. These findings were consistent with a diagnosis of mucinous carcinoma. Extensive work-ups excluded cutaneous metastases from primary visceral mucinous carcinomas. To ensure complete tumour removal, both patients underwent Mohs' micrographic surgery (standard fresh-frozen technique). They remain disease-free 42 and 26 months after surgical excision, respectively. Mohs' micrographic surgery appears to be a rational and effective treatment for this uncommon malignancy.     

Microcystic adnexal carcinoma with sebaceous differentiation: Three cases

Microcystic adnexal carcinoma (MAC) is a low‐grade malignant tumor of the skin. Histologically, this tumor shows a biphasic pattern, with cords and nests of basaloid cells, as well as keratin horn cysts. This biphasic histological appearance has been interpreted by some authors as a sign of double eccrine and folliculosebaceous‐apocrine differentiation, whereas some other authors defend a solely eccrine differentiation. In this context, sebaceous differentiation in MAC would support the first option. However, there are only 3 cases of MAC with sebaceous differentiation in the literature, and all of them were reported before adipophilin was available, which in the appropriate context (eg, testing clear cells for sebaceous vs eccrine differentiation) is very useful. In this study, we present 3 cases of MAC with focal sebaceous differentiation confirmed by immunoexpression of adipophilin in the sebaceous foci.     

A case of sebaceous carcinoma diagnosed in an adolescent male

Sebaceous carcinoma is an uncommon and potentially aggressive malignancy that exhibits sebaceous differentiation. Approximately 75% of cases arise in the periocular region. Sebaceous carcinoma is rare in the pediatric population and its presentation in this age group is not well documented in the dermatopathology literature. We report the case of a 15-year-old male with sebaceous carcinoma who was first seen with a nodular lesion involving the skin of the left orbit/temporal area. A shave biopsy was performed which showed an infiltrative proliferation of basaloid cells that focally exhibited sebaceous differentiation, including the formation of incipient sebocytes. Immunohistochemically, the tumor cells expressed epithelial membrane antigen (EMA) and CK5/6, while a lack of Ber-EP4 was observed. Based upon these attributes, the diagnosis of sebaceous carcinoma was rendered. Subsequent immunohistochemical analysis for a possible DNA mismatch repair enzyme defect revealed that all four mismatch repair gene products showed retained expression, thereby providing no support for the presence of underlying Muir-Torre syndrome. Sebaceous carcinomas are exceptional in the pediatric age group and are rarely documented in the dermatopathology literature. Knowledge that this adult carcinoma can occur mostly in the pediatric age group may aid in the recognition of this uncommon malignancy.     

Trichilemmal Carcinoma Developing in a Burn Scar: A Report of Two Cases

Two cases of trichilemmal carcinoma (TLC) developing in burn scars are reported. In Case 1, a 73-year-old man developed a TLC on his left lower leg five years after a burn. In Case 2, a 43-year-old man developed a cauliflower-like mass on his head 42 years after a burn. Histologically, tumor cells showed a lobular proliferation in continuity with the epidermis. Tumor nests were mostly composed of large atypical cells with clear cytoplasms containing PAS-positive, diastase sensitive materials. Some of the nests showed trichilemmal-type keratinization. These cases were treated only with surgical excision, and there has been no evidence since of local recurrence or metastasis.     

Pure mucinous (colloid) adenocarcinoma of the conjunctiva

Primary mucinous carcinomas of the periorbital region are very rare and often require differential diagnosis of metastatic disease. We describe a case of pure mucinous adenocarcinoma arising in the subconjunctival stroma of the ocular fornix in a female patient with a longstanding history of bilateral ocular cicatricial pemphigoid. Histologically, the tumor was composed of predominantly goblet‐like cells floating in pools of mucin separated by delicate collagenous septa. The initial suspicion was of primary cutaneous mucinous carcinoma and less likely endocrine mucin‐producing sweat gland carcinoma, however the CK7‐/synaptophysin‐/chromogranin‐immunoprofile did not confirm either of the two. Focal areas of the tumor demonstrated peripheral staining for p63 and CK5/6 suggestive of an in situ component. Additional studies showed that the tumor cells were positive for CK20, CDX2, villin and MUC2. Given the final immunophenotype of the tumor, metastatic lesion from the lower gastrointestinal tract had to be ruled out. Thorough clinicoradiological work‐up did not reveal any other primary tumors or evidence of metastatic disease elsewhere. Unique histomorphology, the presence of an in‐situ component and negative clinical investigation suggest that this is a primary mucinous adenocarcinoma arising in the ocular fornix. This case may represent the first report of this entity in the literature.     

Reticulated acanthoma with apocrine differentiation

Reticulated acanthoma with apocrine differentiation (RAAD) represents a rare variant of adnexal neoplasm first described by Ackerman et al. in 1998. It consists of cords and columns of adnexal keratinocytes that form a reticulated pattern. Variable signs of apocrine, sebaceous and follicular differentiation may be present. Since 1998, no further cases of this condition have been published. We report on a lesion excised from the leg of a 46-year-old man, which displayed histopathological features diagnostic of RAAD. Criteria for diagnosis and differential diagnoses are discussed.     

Microcystic adnexal carcinoma with germinative follicular differentiation

Microcystic adnexal carcinoma (MAC) is a low‐grade adnexal carcinoma with controversial lines of differentiation. We present here an example of MAC showing histopathologic findings of germinative follicular differentiation in the form of solid aggregates of trichoblastoma intermingled with neoplastic aggregates of MAC. Immunohistochemical findings, showing positivity for PHLDA1 and negativity for BerEp4 in neoplastic aggregates of trichoblastoma, also supported a germinative follicular differentiation. Follicular differentiation in MAC supports an apocrine line of differentiation for this neoplasm.     

Trichoblastoma,syringocystadenoma papilliferum,desmoplastic trichilemmoma and tumor of the follicular infundibulum with signet‐ring cells,all arising in nevus sebaceus

Herein, we describe a 63‐year‐old male with multiple tumors arising within a nevus sebaceus on the posterior scalp. On histopathologic examination, four distinct tumors were identified: trichoblastoma, syringocystadenoma papilliferum, desmoplastic trichilemmoma and tumor of the follicular infundibulum (TFI). Within the TFI component of the nevus sebaceus, there was intracytoplasmic accumulation of eosinophilic keratin, as shown on pancytokeratin‐stained sections, imparting a signet‐ring appearance to the cells. To our knowledge, this is the first report of signet‐ring cells arising within a TFI occurring in a nevus sebaceus. We discuss this case as well as review the literature on multiple tumors arising within nevus sebaceus and signet‐ring cell changes in primary cutaneous tumors.