Hiding in Plain Sight: An Atypical Presentation of the Uncommon Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a cutaneous neoplasm that is challenging to diagnose secondary to its rarity. We report a case involving a 76-year-old Caucasian female with a seemingly benign skin nodule on her right forearm. Histopathological analysis revealed characteristics of MCC, including uniform round cells with minimal cytoplasm and fine granular chromatin. Immunohistochemical staining confirmed insulinoma-associated protein 1 (INSM1) positivity, a marker with high sensitivity and specificity in localized MCC diagnosis. The subsequent treatment plan involved wide local excision, sentinel lymph node evaluation, and radiation therapy, aligning with therapeutic standards for MCC. Negative positron emission tomography (PET) scans and follow-up for one year have demonstrated no evidence of recurrence or additional lesions. This case demonstrates the challenges in diagnosing MCC and the need for histopathological and immunohistochemical assessments for an accurate diagnosis. Diagnostic markers, INSM1, are important distinguishing factors between MCC and other skin cancers. In conclusion, our case contributes to the literature in diagnosing MCC and successful treatment, while emphasizing the need for immunohistochemical markers for accurate diagnosis and guiding therapeutic decisions.

Malignant wound aetiology, diagnosis and management: a case series and literature review

OBJECTIVE

Malignant wounds develop when neoplastic cells invade the skin either locally or by lymphatic and haematogenous spread. They can present as hard-to-heal wounds and underlying causes include: primary skin cancer; metastasis of extracutaneous primary malignancy; malignant transformation of a hard-to-heal wound; iatrogenic injury; and cutaneous forms of cancers of non-skin origin. High clinical suspicion for a malignant wound should be confirmed with skin biopsy. The aim of this case series is to highlight a combination of both clinically clear cutaneous malignancies and not-so-obvious wounds caused by malignancy.

METHOD

This case series examines patients with malignant wounds of varying aetiology and appearance. For each case, we explain the pathophysiology, atypical features, diagnostic approach and treatment. We also discuss types of wound biopsy and general wound management principles.

RESULTS

Among the 11 cases analysed using descriptive statistics, median wound duration before presentation at our clinic was one year, while median age at presentation was 65 years. Our case series included the following diagnoses: cutaneous metastasis of invasive ductal carcinoma of the breast (n=2); cutaneous metastasis of colorectal adenocarcinoma (n=1); Marjolin's ulcer (n=1), basal cell carcinoma (BCC) (n=2), primary cutaneous squamous cell carcinoma (SCC) (n=1), metastatic malignant melanoma (n=1), cutaneous T-cell lymphoma (n=1), cutaneous angiosarcoma (n=1), Kaposi sarcoma (n=1) and recurrent tonsillar SCC with osteoradionecrosis (n=1); one case had both BCC and SCC.

CONCLUSION

Punch and excisional biopsies were the most frequently used diagnostic techniques. Local wound therapy addressed bleeding, malodour, exudate, pain and infection. However, wound healing is usually achieved once the underlying malignancy is treated. In advanced or metastatic disease, palliative wound care aims to prevent exacerbation of existing wounds and focuses on patient comfort.

An Unusual Case of an ALK-Negative Epithelioid Fibrous Histiocytoma in the External Auditory Canal

This article represents the first reported case in the external auditory canal of epithelioid fibrous histiocytoma (EFH), a rare benign cutaneous epithelioid neoplasm. Immunostaining revealed uncommon negative staining for anaplastic lymphoma kinase (ALK) expression. This case and literature review outline the diagnostic strategy for this highly unusual neoplasm. Laryngoscope, 2024.

Bullous Pilomatrixoma After COVID-19 Vaccination

Pilomatrixoma, or calcifying epithelioma of Malherbe, is a benign tumor with differentiation toward the hair matrix cells and is one of childhood's most common epithelial tumors. Bullous pilomatrixoma has an extremely low incidence of occurrence, usually appears in the upper extremities, and is frequently associated with trauma. We report the case of a bullous pilomatrixoma in a patient with a rapid-growing neoformation one month after receiving a coronavirus disease 2019 (COVID-19) vaccine in his left upper arm, and we discuss whether the bullous appearance is part of the biology of the tumor or a secondary anetoderma.

Cutaneous Vascular Neoplasms of Uncertain Biological Behavior

Neoplasms of uncertain biological behavior present physicians with a genuine conundrum in practice. Cutaneous vascular neoplasms within this category are exceedingly rare, possessing significant gaps and uncertainty in many facets of clinical practice. Firstly, lesions were selected for review based on their categorization as indeterminate behavior, indicating the potential for local recurrence and rarely metastasize. After identification of the target lesions, a comprehensive review of the literature using national databases produced several landmark studies and case series regarding these neoplasms. Limiting the review to only cutaneous limited tumors narrowed the pool of studies; however, quite a large sum of papers remained. Examination of each paper yielded beneficial results on diagnosing, effective treatments, follow-up findings, and prognosis for each indeterminate lesion discussed. Overall, the literature search combined the molecular, histologic, immunohistochemical, surgical strategies to develop an up-to-date and comprehensive framework to guide physicians when encountering such lesions. The tumors reviewed include: kaposiform hemangioendothelioma, endovascular papillary angioendothelioma, pseudomyogenic hemangioendothelioma, retiform hemangioendothelioma, epithelioid hemangioendothelioma, and composite hemangioendothelioma.

Primary cutaneous malignant perivascular epithelioid cell tumor: Case of a rare tumor with review of the literature

Perivascular epithelioid cell tumors (PEComas) are mesenchymal neoplasms with characteristic epithelioid or spindled cytomorphology that typically grow around blood vessels. These tumors are phenotypically and immunohistochemically distinct, expressing markers of both melanocytic and smooth muscle differentiation. Herein, we describe a case of histopathologically malignant cutaneous PEComa without metastatic spread, with review of the pertinent literature. Telescoping punch biopsy demonstrated an epithelioid neoplasm with marked atypia, hypercellularity, and increased mitotic activity. Immunohistochemical stains for HMB-45, NK1-C3, PGP9.5, MiTF, CD10, and CD68 were positive within tumor cells. In addition, there was diffuse expression of caldesmon and focal cytoplasmic staining for smooth muscle actin on the excision specimen. The patient underwent treatment with surgical excision with adjuvant radiation and surveillance computed tomography (CT). The patient remains free of recurrence or metastatic disease after 10 months of follow-up. To our knowledge, this is only the third reported case of a malignant cutaneous PEComa reported in the literature to date.

A lobulated mass on the upper back with prominent vasculature: A giant basal cell carcinoma

Basal cell carcinoma (BCC) is characterized by slow but locally invasive growth. Although there is low metastatic potential, if not treated early, these skin cancers can lead to significant morbidity and mortality. In this case report, we present a man with a neglected BCC that developed into what is termed a giant BCC or one that is greater than 5 cm. This tumor was discovered only upon workup of orthostatic lightheadedness and iron deficiency anemia. Although rare, basal cell carcinoma must be included on the differential of a large cutaneous lesion and may be a source of significant blood loss.

Molecular profiling of a primary cutaneous signet-ring cell/histiocytoid carcinoma of the eyelid

Primary cutaneous signet-ring cell/histiocytoid carcinoma of the eyelid is a rare and aggressive neoplasm. Fewer than 50 cases have been reported in the literature, and the genetic driving mutations are unknown. Herein, we present a case of this rare disease along with the results of molecular profiling via targeted next-generation sequencing. The patient is an 85-year-old man who presented with left eyelid swelling initially thought to be a chalazion. After no response to incision and drainage and antibiotics, an incisional biopsy was performed. Histopathologic sections revealed a proliferation of cells with signet-ring and histiocytoid morphology arranged singly and in cords infiltrating the dermis, subcutaneous tissue, and muscle. The lesional cells strongly expressed cytoplasmic cytokeratin 7 and nuclear androgen receptor. Next-generation sequencing revealed a CDH1 mutation, which is known to confer signet-ring morphology in other carcinomas. Pathogenic mutations in NTRK3, CDKN1B, and PIK3CA were also detected. To our knowledge, this is the first documented genetic analysis of this rare disease with findings that offer insights into disease pathogenesis and potential therapeutic targets.

Eccrine Porocarcinoma: A Case Report of a Rare and Aggressive Cutaneous Tumour

Eccrine porocarcinoma (EPC) is an extremely rare, adnexal carcinoma that represents less than 0.01% of all cutaneous malignancies. An aggressive tumour with a high recurrence rate, it has a tendency to metastasise to regional lymph nodes. Once metastasis has occurred, mortality rate increases to 75%-80% and thus survival is dependent on adequate and timely resection of the lesion. EPCs are frequently missed as a differential diagnosis due to their rarity and non-specific appearance, which can lead to serious consequences for patients. Consequently, EPCs are an important diagnosis for clinicians to be aware of and consider when evaluating cutaneous lesions. 

We present a case of EPC of the knee, which was initially misdiagnosed as a benign lesion on magnetic resonance imaging (MRI). We discuss the use of MRI in aiding assessment of EPCs.

Fungal Masquerader: A Case Report of Extramammary Paget's Disease Treated with Radiotherapy

An 83-year-old Caucasian male presented with a pruritic erythematous patch to his right inguinal region, which he had contracted five months ago. After months of topical antifungal and steroid therapies, the patient was referred to dermatology due to a lack of lesion improvement. A 5.0 mm punch biopsy with immunohistochemical staining revealed the presence of pleomorphic nuclei with cytoplasm replete with mucin, suggestive of superficial extramammary Paget's disease (EMPD). As he was reluctant to undergo a surgical assessment, the patient underwent consultation and management with 30 sessions of superficial electron beam radiotherapy. A week after the completion of radiation therapy, the patient's skin exhibited minimal erythema with surrounding hyperpigmentation to the affected inguinal skin, suggesting clearance of the disease. This case highlights the importance of an accurate diagnosis in a timely manner as neoplastic cases have a metastatic risk with potentially devastating results.

Case of probable spontaneous regression of Merkel cell carcinoma combined with squamous cell carcinoma without surgical intervention

Merkel cell carcinoma (MCC) is a rare but more lethal cutaneous cancer than melanoma. However, spontaneous regression of a number of MCC has been reported, although the cause of this regression remains unclear. In most cases, MCC regresses after a surgical procedure, for example, biopsy. Herein, we report a case of Merkel cell polyomavirus-negative MCC coincident with squamous cell carcinoma (SCC) that underwent true spontaneous regression without biopsy. One month after the patient's first visit, clinical examination revealed that the tumor had not grown, but its surface showed changes in texture and color. Histopathologically, the excised specimen was indicative of MCC coincident with SCC and showed extensive necrosis in the upper portion of the tumor, numerous caspase-3-positive apoptotic cells, an accumulation of CD68-positive foam cells and vascular invasion. These findings suggested that the tumor had regressed. We hypothesize that extensive coagulative necrosis resulting from an insufficient local blood supply triggered the shedding of some products or components of MCC and SCC, which in turn induced antitumor immunity against both lesions.

Skin lesions serve as clues to relapse of pediatric blastic plasmacytoid dendritic cell neoplasm

A 10-year-old girl with a history of blastic plasmacytoid dendritic cell neoplasm, a rare malignancy in children, presented with recurrent skin eruptions beginning while on maintenance chemotherapy, including mildly pruritic skin-colored plaques, tender indurated nodules, and violaceous bound-down plaques. This case highlights an unusual presentation of relapsed blastic plasmacytoid dendritic cell neoplasm on chemotherapy, with skin lesions providing important clues to the progression of systemic disease.

Subcutaneous melanocytoma mimicking a lipoma: a rare presentation of a rare neoplasm with histological, immunohistochemical, cytogenetic and molecular characterization

Melanocytoma are the melanocytic tumors originating from leptomeningeal melanocytes. Melanocytomas are commonly seen in the central nervous system (CNS) and are often associated with neurocutaneous melanosis (NCM). However, simultaneous presentation of intra-axial and extracranial melanocytoma is a very rare event. Here, we report a unique case of 21-year-old male with intermediate-grade subcutaneous (SC) melanocytoma, mimicking lipoma, occurred synchronously with an intracranial melanocytoma, not associated with NCM. A 21-year-old Caucasian male presented to the emergency department (ED) with severe vertigo and vomiting. A magnetic resonance imaging (MRI) of the brain was performed at the ED, which revealed an SC mass in the right occipital scalp and a right cerebellopontine angle (CPA) mass. Excision of the SC mass revealed a well-circumscribed highly pigmented melanocytic tumor. The SC mass tumor cells were positive for melanocytic lineage markers. The histopathological features were between benign melanocytomas and malignant melanomas. The Ki67 and PHH3 IHCs confirm the intermediate grade of the tumors. An array-CGH (comparative genome hybridization) and next-generation sequencing analysis of the tumor DNA extracted from the formalin-fixed paraffin-embedded tissue reveals chromosome 6p gain and p.Q209P mutation in the GNAQ gene, respectively, consistent with the diagnosis of intermediate-grade melanocytoma.

A rare cutaneous adnexal neoplasm: cystic panfolliculoma

A cystic panfolliculoma is a benign follicular neoplasm which recapitulates several portions of the hair follicle. The patient was a 64-year-old Caucasian female who presented with a new growth on her right forearm. The lesion had slowly enlarged over the previous 11 months. She complained of it bleeding on several occasions and being very tender when touched. On exam was an 8 mm firm pink papule which appeared slightly eroded. The growth was excised in clinic. Histology showed a well-circumscribed neoplasm with foci of matrical, infundibular, inner and outer root sheath differentiation. A BerEp3 labeled focal areas of follicular germinative differentiation at the periphery of the proliferation. The lesion was narrowly excised in the available planes of section. The surgical site healed well and there are no residual symptoms from the tumor.

Advances in the clinicopathological and molecular classification of cutaneous mesenchymal neoplasms

In recent years, there have been several important refinements in the classification of cutaneous mesenchymal neoplasms, including the description of new tumour types, along with the identification of novel and recurrent molecular genetic findings. In addition to providing new insights into tumour biology, many of these advances have had significant clinical consequences with regard to diagnostics, management, and prognostication. Newly described entities include pseudomyogenic haemangioendothelioma, haemosiderotic fibrolipomatous tumour, and fibroblastic connective tissue naevus, which are reviewed in the context of the principal differential diagnoses and significant clinical implications. Genetic characterization of several soft tissue tumour types that occur in the skin has resulted in the identification of diagnostically useful markers: ALK gene rearrangement with corresponding ALK protein expression by immunohistochemistry in epithelioid fibrous histiocytoma; the WWTR1-CAMTA1 fusion gene with CAMTA1 protein expression in epithelioid haemangioendothelioma; MYC amplification and overexpression in radiation-associated angiosarcoma; and EWSR1 gene rearrangement in cutaneous myoepithelial tumours. Finally, the classification of intradermal smooth muscle tumours and unclassified/pleomorphic dermal sarcoma has been refined, resulting in both improved classification and improved prognostication. Many of the tumour types listed above are encountered not only by specialist dermatopathologists, but also by practising general surgical pathologists, and this review should therefore provide a widely applicable update on the histological and molecular classification of cutaneous mesenchymal neoplasms, along with the appropriate use of ancillary diagnostic tests, in particular immunohistochemistry, in the evaluation of such lesions and their histological mimics.

A retrospective, multicenter analysis of the predictive value of mitotic rate for sentinel lymph node (SLN) positivity in thin melanomas

BACKGROUND

There is a paucity of studies to substantiate whether the presence of a single mitosis justifies sentinel lymph node (SLN) biopsy (SLNB) in thin melanomas.

OBJECTIVE

We sought to determine if mitotic rate is associated with SLNB outcome when taking into account other prognostic factors.

METHODS

All cases of melanoma that underwent SLNB in the province of Alberta, Canada, between 2007 and 2013 were reviewed through a provincial tumor database.

RESULTS

A total of 1072 patients fulfilled inclusion criteria. When analyzing all melanomas regardless of thickness, mitotic rate was a good predictor of SLN status. When stratified by Breslow thickness, only intermediate melanomas (1.01-2.0 mm) demonstrated a significant relationship between mitotic rate and positive SLN status (P = .010). For melanomas 1 mm or smaller, mitotic rate was not associated with SLN status. A statistically significant interaction was identified between Breslow thickness and mitotic rate such that for decreasing Breslow depth, the effect of mitotic rate on SLNB status diminished (P = .028).

LIMITATIONS

The study was retrospective in nature. There is underlying variability in mitotic rate reporting methods over time, and between different dermatopathologists.

CONCLUSIONS

Mitotic rate does not have unequivocal utility in predicting SLNB status in thin melanomas. There is a significant interaction between mitotic rate and Breslow depth, such that the predictive value of mitotic rate on SLN positivity may be dependent on Breslow thickness.

Multiple apocrine poromas: a new case report

Apocrine poromas are rare and distinctive benign adnexal neoplasms featuring tumor cells differentiating toward folliculosebaceous-apocrine units. We report an extremely rare case with multiple apocrine poromas in a single patient. Fifteen tumors were distributed on the head, neck, forearm and axilla of a 74-year-old man. All tumors were mostly composed of poroid cells that surrounded variably sized duct spaces, some of which exhibited decapitation secretion. The poroid cells were continuous with infundibulum-like structures that contained aggregates of mature sebocytes. The patient had no family history of similar tumors and no history of immunosuppressive therapy. This is the first report of multiple apocrine poromas, suggesting that predisposing genetic factors might play a part in the development of the tumors.

Glomus-like bodies within a neurofibroma: a novel neoplasm arising in neurofibromatosis type 1 or a coincidence?

Neurofibromatosis type 1 is a relatively common genetic disorder with variable phenotypes. Tumors with features of both glomus tumors and neurofibromas are exceedingly rare in literature. Herein, we report a not yet described neoplasm with features of both a glomangioma/glomus tumor and a neurofibroma arising in a patient with segmental neurofibromatosis. Our case report supports the theory of a common lineage/ancestor cell between neurofibromas and glomus tumors and adds it to the spectrum of neoplasms that may arise in the setting of Von Recklinghausen's disease.

SOX-10 expression in cutaneous myoepitheliomas and mixed tumors

BACKGROUND

SOX-10 expression can be demonstrated by immunohistochemistry in salivary gland myoepitheliomas, but its expression in cutaneous myoepitheliomas and in cutaneous mixed tumors with prominent myoepithelial cells has not been studied.

METHODS

We assessed the staining pattern of SOX-10 in five cutaneous myoepitheliomas and six cutaneous mixed tumors with a prominent myoepithelial component among both the myoepithelial cells and cells lining lumens. In addition, we examined the staining of S100, microphthalmia-associated transcription factor (MiTF), keratin cocktail, HMK903, smooth muscle actin (SMA) and epithelial membrane antigen (EMA).

RESULTS

SOX-10 positivity was seen in three of five (60%) cutaneous myoepitheliomas and in the myoepithelial cells of all cutaneous mixed tumors. SOX-10 expression on the cells lining the glandular structures in mixed tumors was variable. All myoepitheliomas and mixed tumors stained positively with S100 and negatively with MiTF. Pan-keratin, HMK903, SMA and EMA showed variable expression.

CONCLUSIONS

SOX-10 is a relatively reliable marker for staining cutaneous myoepitheliomas. Cutaneous myoepitheliomas are notoriously difficult to diagnose, and the addition of SOX-10 to the repertoire of stains that can label this tumor is of practical utility. These results further support that cutaneous myoepitheliomas and cutaneous mixed tumors exist on a morphologic and immunophenotypic spectrum.

Extrafacial indolent CD8-positive cutaneous lymphoid proliferation with unusual symmetrical presentation involving both feet

Indolent CD8+ cutaneous lymphoid proliferation represents a recently described entity among cutaneous T-cell lymphomas that typically presents with solitary skin lesions on the face or at acral sites and usually follows an indolent clinical course. Histopathologically, this entity is characterized by a dense dermal infiltrate of non-epidermotropic, small- to medium-sized pleomorphic CD8+ T-cells of the non-activated cytotoxic phenotype showing a clear-cut grenz zone and a low proliferation index. Distinction from otherwise aggressive T-cell lymphomas bearing a cytotoxic CD8+ phenotype is fundamental. We herein present an unusual case of indolent CD8+ cutaneous lymphoid proliferation presenting in bilateral symmetrical distribution on both feet and lacking the otherwise described grenz zone. Our case widens the spectrum of possible clinical and histomorphological variations of this entity. Taking into account the distinctive and unique clinical and microscopic features of all hitherto published cases of indolent CD8+ cutaneous lymphoid proliferation we suppose that this lymphoma subtype has to be included as a new and distinct entity in the World Health Organisation (WHO)-/European Organisation for Research and Treatment of Cancer (EORTC)-classification of cutaneous lymphomas.

High immunohistochemical nestin expression is associated with greater depth of infiltration in dermatofibrosarcoma protuberans: a study of 71 cases

BACKGROUND

Dermatofibrosarcoma protuberans (DFSP) was recently shown to express nestin, a marker that has been associated with poorer prognosis when present in high levels in certain tumors. The objective of this study is to explore the association between high nestin expression and deep invasion.

METHODS

We performed a retrospective, observational study in which we evaluated the degree of nestin expression in 71 DFSP. The odds of fascial involvement was calculated before and after adjusting for the following confounders: age, sex, tumor size, time to diagnosis, tumor site, the presence of fibrosarcomatous areas, pleomorphism, number of mitotic figures and predominant histopathologic pattern. We also calculated the Spearman Rho correlation coefficient between nestin staining intensity and depth of invasion.

RESULTS

Nestin immunopositivity was found in 98.6% of the tumors, and high expression levels were significantly associated with invasion of the fascia. The odds of fascial involvement in tumors with strong nestin staining was 6.56 (p = 0.001) before adjustment for confounders and 14.86 after adjustment (p = 0.007). The Spearman rho correlation coefficient between nestin expression and deep invasion was 0.287 (p = 0.015).

CONCLUSION

High inmunohistochemical nestin expression appears to be associated with deeper invasion in DFSP.

Cutaneous meningioma: a potential diagnostic pitfall in p63 positive cutaneous neoplasms

Cutaneous meningiomas are divided into three groups. Type I lesions present at birth and are derived from ectopic arachnoid cells. Type II lesions usually present in adults and are derived from arachnoid cells surrounding nerve bundles. Type III lesions are due to direct extension or metastasis from dural-based neoplasms. Dural-based meningiomas are known to express p63. The aim of our study is to examine the expression of p63 in type II and type III meningioma. Two cases of cutaneous meningioma (type II and type III) were evaluated for the expression of p63, EMA, CK 5/6, S100 and CD31. The cells of interest were spindled to epithelioid and arranged in a whorling pattern. Immunohistochemical staining showed expression of EMA and p63 in both cases, while stains for CK 5/6, S100 and CD31 were negative. Among cutaneous tumors, p63 is considered a marker of epithelial derivation, as it is positive in epidermal and adnexal neoplasms. It is important to be aware of p63 expression in the context of cutaneous meningioma to avoid misinterpretation as an epithelial tumor. On the basis of our small study, it is unlikely that p63 expression would be helpful in distinguishing between type II and type III meningioma, as both may be p63-positive.

Bilateral areolar leiomyomas in a patient undergoing BRAF inhibition therapy for melanoma

BRAF inhibition therapy, used to treat melanomas with BRAF mutations, is associated with both neoplastic and non-neoplastic cutaneous side effects including squamous cell carcinomas, warty dyskeratomas, verrucous keratoses, photosensitivity and widespread eruptions that present histopathologically as acantholytic dyskeratosis. We report a case of a patient undergoing BRAF inhibition therapy for disseminated melanoma with a V600E mutation who developed bilateral areolar leiomyomas, one of which was biopsied and the other of which resolved after discontinuation of vemurafenib therapy. To our knowledge, this is the first reported case of a mesenchymal neoplasm developing in association with BRAF inhibition therapy.

A clinically invisible melanoma

We report a case of an amelanotic lentigo maligna incidentally found on a shave biopsy in an 87-year-old woman. Amelanotic lentigo maligna is a rare variant of lentigo maligna. It is often reported as presenting as erythematous scaly macules and is usually confused as benign dermatoses. Here were present a case of amelanotic lentigo maligna with no visible or palpable features.

Atypical fibroxanthoma: an unusual skin neoplasm in xeroderma pigmentosum

Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder related to defective deoxyribonucleic acid (DNA) repair. Various cutaneous manifestations related to ultraviolet (UV) damage characterize the clinical course. Primary malignant cutaneous neoplasms like squamous cell carcinoma, basal cell carcinoma and malignant melanoma have been reported. Atypical fibroxanthoma is a rare dermal neoplasm occurring in UV-damaged skin. We report an unusual case of atypical fibroxanthoma in a 20-year-old male with XP.