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BACKGROUND. Review of the literature reveals that malignant spiradenomas are rare and may be fatal, and typically manifest as rapid enlargement in long-standing spiradenomas. OBJECTIVE. The present tumor was removed 2 months after it was first noted by the patient. A case of what we believe is the earliest stage of malignant transformation within spiradenoma is reported. METHODS. Case report and literature review. RESULTS. The region with malignant transformation was characterized by nuclear pleomorphism, loss of two cell types, and increased mitotic activity with atypical mitoses. Small infiltrating duct-like structures were seen. The large aggregates and sheets of malignant cells described in long-standing tumors were not seen. CONCLUSION. We ascribe the early detection of this tumor to increased public awareness of the importance in seeking early treatment of skin lesions. Histologic examination of tins stage may eventually outnumber the now more commonly described latter stages. [ABSTRACT FROM AUTHOR]

Abstract: Insulin-derived amyloidosis (AIns) is a rare iatrogenic subtype of cutaneous amyloidosis occurring at frequent insulin injection sites. Here, we describe 2 cases of AIns accompanied by acanthosis nigricans (AN)-like changes, a rare finding which has been reported fewer than 5 times in the literature. We also report the first case of an AIns nodule being misdiagnosed as a keloid. Both of our patients presented with asymptomatic, hyperkeratotic, pigmented plaques at frequent insulin injection sites, and histopathologic examination showed (1) nodular aggregates of amyloid demonstrating apple-green birefringence with Congo red staining and (2) AN-like features, such as epidermal papillomatosis, hyperkeratosis, and hyperpigmentation. Accurate diagnosis of AIns is crucial, because repeated insulin injection into a nodule can impair glycemic control. However, misdiagnosis is common, as observed with our second patient, whose AIns nodule was misdiagnosed by an outside provider as a keloid, perhaps because of the presence of AN-like features. Our case report adds to the limited but growing body of literature on AIns and significantly increases the number of reported cases of AIns with AN-like features, an even rarer phenomenon., Competing Interests: The authors declare no conflicts of interest. Dr. Rosalie Elenitsas has no conflicts of interest relevant to this manuscript. However, for full disclosure: she has received royalties from Wolters Kluwer as a textbook editor., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Abstract: Cutaneous ganglioneuromas (GNs) are exceptionally uncommon tumors, and many reported cases describe association with overlying epidermal hyperplasia that may be interpreted as seborrheic keratosis (SK) or SK-like proliferation. We report 5 cases of cutaneous GN in adult patients; all of which were discovered incidentally in the immediate vicinity of epidermal hyperplasia. A review of the literature demonstrates the current-although likely imperfect-understanding of the etiopathogenesis of both SK and GN in the skin. We explore the putative pathophysiologies of other common, well-characterized skin lesions and, taking them into account, provide rationale for the coexistence of cutaneous GN with overlying SK and SK-like epidermal changes. However, we ultimately acknowledge a dilemma of causality and, given the rarity of their co-occurrence, objectively question whether occasional cameo appearances by GN lying subjacent to SK and SK-like hyperplasia may be due merely to chance., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Competing Interests: The authors declare no conflicts of interest.

Competing Interests: The authors declare no conflicts of interest.

In classical clinical perniosis (chilblains), the presence of atypical lymphocytes with immunohistochemical staining positive for CD30 is unusual and rarely reported. Here we report 2 cases of clinical perniosis, one in a 16-year-old girl and another in a 67-year-old woman. The biopsies revealed lymphocytic infiltrates, papillary dermal edema, and atypical cells highlighted with a CD30 immunohistochemical stain. Our cases demonstrate the importance of clinicopathologic correlation in the assessment of CD30 positive lymphocytes in benign nonneoplastic conditions. Dermatopathologists must be aware of this potential histologic pattern in perniosis to prevent misdiagnosis and overtreatment of this condition.

Microcystic adnexal carcinoma (MAC) is an uncommon, locally aggressive, malignant cutaneous tumor with pilar and eccrine differentiation. Mohs micrographic surgery is the treatment of choice for this condition, but specific histological findings can complicate MAC removal and leave doubt as to whether the tumor has been completely removed. Here we describe the clinical and pathological characteristics of a case in which a patient with an MAC underwent multiple reexcisions because of the presence of benign subclinical syringomatous proliferations adjacent to the primary lesion. Our case raises awareness of syringomatous proliferation, a benign process histologically similar but behaviorally distinct from a primary MAC. This experience highlights the importance of continued communication between dermatopathologists and dermatologic surgeons in providing quality patient care.

The term "induction" has been used to describe epidermal changes overlying a dermatofibroma (DF). Follicular induction is most often associated with DF, but can be observed in other lesions, including focal mucinosis, nevus sebaceous, seborrheic keratosis, wart, neurofibroma, and scars. Dermatofibrosarcoma protuberans (DFSP) is a malignant fibrohistiocytic tumor that may be difficult to distinguish from DF. In contrast to DF, the epidermis overlying DFSP is usually attenuated or ulcerated. Here, we report a case of DFSP exhibiting follicular induction of the overlying epidermis. This epidermal change has been rarely reported in DFSP and may present a diagnostic pitfall in superficially sampled lesions.

: Postirradiation morphea is a rare complication of radiation therapy which often presents as an erythematous indurated plaque and may be mistaken for recurrent or metastatic carcinoma. Histologic examination is essential for distinguishing postirradiation morphea from malignant processes and from other types of radiation dermatitis and infectious cellulitis. We report a case of postirradiation morphea and review the postirradiation morphea literature. In addition, we summarize the clinical and histopathologic characteristics of the various forms of postirradiation skin disease, including postirradiation morphea; acute, subacute, and chronic radiation dermatitis; and radiation recall dermatitis.

There are multiple clinical and histopathologic presentations of cutaneous metastases. We report 3 cases of visceral malignancies metastasizing to the skin and histopathologically mimicking interstitial granulomatous processes, including granuloma annulare and interstitial granulomatous dermatitis. Histopathologic examination of skin biopsy specimens, from our patients with established histories of cancer, revealed malignant carcinoma-derived cells organized in an interstitial pattern. Of note, some of the lesional cells appeared relatively bland without significant cellular atypia. When examining a skin biopsy of a new lesion from a patient with a history of internal malignancy, it is important to perform immunohistochemical staining to evaluate for metastatic disease, even if the histological pattern is suggestive of a benign interstitial granulomatous process.

Equestrian perniosis (EP) is a rare condition in which patients develop tender burning nodular plaques on their bilateral thighs after riding in the cold. These lesions tend to resolve rapidly with minimal exposure to cold, and wearing loose, layered warm clothing. Unlike acral perniosis, EP has no known systemic disease associations, although 2 reported cases did have elevated cold agglutinins. The histology of this disease is similar to perniosis; however, EP is distinct in that the perivascular lymphocytic infiltrate prominently involves the fat. In this case report, we discuss the clinical and histological findings in 2 cases of EP, including the first documented in a man.

Nodular scleroderma, also known as keloidal scleroderma, is a rare form of scleroderma that may occur with either systemic sclerosis or localized scleroderma. Clinically, this disorder is characterized by keloidal nodules that form in sclerodermatous areas. These nodules may histologically show the presence of keloidal collagen. Because of the rarity of this condition, clinicians may not be familiar with the clinical and histologic features relevant to this scleroderma variant. In this report, we describe 2 cases of nodular scleroderma.

Background: Desmoplastic melanoma (DMM) is an uncommon melanoma variant with a distinct morphology, including a prominent spindle cell component with fibrosis, as well as a distinct immunohistochemical profile. Histologically, the spindle cell component of DMM can be confused with sclerotic/desmoplastic nevi, nonpigmented blue nevi, scar, and neural tumors. The histological distinction between sclerotic/desmoplastic/blue nevi and DMM using standard light microscopic techniques can be exceedingly subtle. Therefore, we investigated whether immunohistochemical staining for Melan-A and Ki-67 expression can be used to discriminate these lesions, distinguishing between epithelioid and spindle cell compartments of the lesions., Design: Fifty cases of DMM and 13 cases of sclerotic/desmoplastic/blue nevi were identified. Standard immunohistochemical techniques were used with antibodies towards HMB-45, Melan-A (A103), and Ki-67; 43 of 50 DMM cases were available for staining with Melan-A, 42 of 50 for HMB-45, and 31 of 50 cases were stained with Ki-67. All 13 nevi were stained for Melan-A and 8 for Ki-67. Immunoreactivity to Ki-67 antibody was scored as 0 to 5%, 6 to 10%, 11 to 30%, or greater than 30% positive tumor cells., Results: Only 3 of 43 and 3 of 42 of spindle cell compartments of DMMs were positive for Melan-A and HMB-45, respectively. Focal staining of epithelioid cells in the junctional component or superficial dermis was observed in 33% (14/43). In contrast, 100% of the 13 nevi were strongly positive for Melan-A (P < 0.001). Seventeen melanomas (55%) were 0 to 5% positive for Ki-67, five (16%) fell into the 6 to 10% category, three (10%) were between 11 and 30%, and six (19%) were at least focally greater than 30% positive. All 8 nevi (100%) had less than 5% positive cells for Ki-67 (P = 0.02), with only 2 cases having more than 2% positive cells., Conclusion: The sclerotic/desmoplastic and hypopigmented blue nevi were uniformly positive for Melan-A, while the vast majority of DMM were negative in their spindle cell compartments. Melan-A is very useful in distinguishing between DMM and sclerotic nevi. Ki-67 appears to be an inconsistent marker for DMM. However, a high labeling index (over 5%) may be used as a clue in diagnosing DMM.

DNA microarrays, microscopic grids of DNA, can be used to assess gene expression within a particular cell or cell population. Since DNA from thousands of genes can be hybridized and analyzed in one experiment, researchers can globally characterize genes expressed in normal and various pathologic states. To accurately assess the differences between normal and pathologic states, one derives cDNA from control and diseased tissue specimens for genes expression profiling. For these reasons, microarray technology may be of particular interest to dermatopathologists and dermatologists interested in understanding cutaneous disease because these physicians have access to tissue specimens. In addition, microarray technology is an efficient way of identifying molecules expressed in a cell population; therefore, it can be used to search for unique immunohistologic markers. To this end, we have used microarray technology to define differences in the gene expression profile of nevi and melanomas. In this manuscript, we discuss the results of our study, which confirm previously known differences in gene expression between melanoma and nevi. While a few genes appear slightly overexpressed in nevi, a number of genes involved in regulating cell proliferation were upregulated in melanoma, such as cyclin D1, cdc2-related protein kinase, c-Myc binding protein, early growth response protein 1, and pleiotrophin. "Housekeeping" genes such as glyceraldehyde 3-phosphate dehydrogenase were expressed at similar levels in melanoma and nevi. Surprisingly, a majority of genes were expressed at similar levels in both nevi and melanoma. Based on this study, DNA microarray technology appears to be a valuable tool for identifying genes that may be specifically expressed in cutaneous lesions.