Subepidermal calcified nodule presenting as a cutaneous horn: two cases and a review of the literature.

Subepidermal calcified nodules are an uncommon subtype of idiopathic calcinosis cutis. Morphologically, this entity typically present as a single, well-circumscribed, white-yellow nodule. Based on clinical appearance alone, subepidermal calcified nodules are frequently misdiagnosed and often requires histological confirmation. We describe two cases of subepidermal calcified nodules presenting atypically as cutaneous horns. Subepidermal calcified nodules presenting as a cutaneous horn has rarely been reported; on review, there are fewer than 10 such cases have been described within the past 30 years. The cases described here illustrate the clinical variety and should increase awareness of subepidermal calcified nodules presented.

Cutaneous metastasis of primary diffuse large B-cell lymphoma of the central nervous system developing 4 years after complete remission: Diagnosis confirmed by comparison of clones.

B-cell lymphoma of the central nervous system (CNS) is a rare malignancy with diffuse large B-cell lymphoma (DLBCL) variant being most common. Although DLBCL has a high propensity to relapse locally within the CNS, only a few cases of cutaneous metastasis have been described in the literature. We present a unique case of cutaneous metastasis of a primary DLBCL of the CNS in a 79-year-old man who was in clinical remission for 4 years until presenting with a lesion in the left adrenal gland and cutaneous nodules on the left flank. Skin biopsy specimen revealed a diffuse dermal infiltrate of atypical B-cell lymphocytes with expression of CD20, BCL-2, BCL-6, and MUM-1, suggestive of DLBCL. For differentiation between another primary or a recurrent process, immunoglobulin kappa (IgK) light chain gene rearrangement was performed and demonstrated that the DLBCL of the skin and CNS were of the same clonal origin. Restaging computerized tomography after initiating chemotherapy and daily ibrutinib showed complete resolution of the left adrenal mass and resolving cutaneous lesions. Our case demonstrates the rare, late cutaneous metastasis of DLBCL of the CNS and highlights the importance of genetic testing for the distinction between the primary and secondary lesions.

Neutrophils in Fixed Drug Eruptions: Correction of a Mistaken Hypothesis.

ABSTRACT: Classical histopathological findings of fixed drug eruption (FDE) include a lichenoid/interface dermatitis and perivascular infiltrate in the upper and deep dermis composed of lymphocytes and eosinophils accompanied by pigment incontinence. The presence of neutrophils is also an established finding but is less investigated. Sporadic cases of "neutrophilic FDE" have been reported and suggested as a separate entity, a rare variant, or an early stage of the condition. In this article, we report 16 cases of FDE with quantitative analysis showing that neutrophils are relatively common in FDE (68.8%) and that cases with abundant neutrophils had a significantly shorter onset-to-biopsy interval (3.7 vs. 16.9 days, P < 0.023). Our findings support that neutrophilic FDE more likely represents the early phase of FDE rather than a different entity. The presence of neutrophils expands the histopathological differential diagnosis of FDE to include neutrophilic dermatosis, signifying the value of clinical correlation.

Basaloid Follicular Hamartoma: An Additional Criterion of Nevoid Basal Cell Carcinoma Syndrome.

ABSTRACT: Basaloid follicular hamartoma (BFH) is a rare, benign follicular neoplasm which typically presents as brown to skin-colored papules on the face, scalp, and trunk. Histologically, BFH consists of cords and strands of basaloid cells forming cystic structures with scant stroma and should be distinguished from infundibulocystic basal cell carcinoma to avoid overly aggressive treatment. Although BFH has been found to be associated with distinct syndromes, including alopecia, myasthenia gravis, and cystic fibrosis, there is often clinical, histopathologic, and genetic overlap with nevoid basal cell carcinoma syndrome (NBCCS). In this article, we describe a case of a 13-year-old patient with NBCCS who presented with multiple BFHs and propose that it its inclusion into the diagnostic criteria for NBCCS be considered.

Improvement of Unilateral Breast Hypoplasia With Oral Spironolactone in a Patient With Becker Nevus Syndrome.

Becker nevus (BN) is a benign cutaneous smooth muscle hamartoma that presents with a hyperpigmented patch or plaque with or without hypertrichosis.1 BN may be associated with ipsilateral breast hypoplasia or other musculoskeletal abnormalities, an association which has been termed Becker nevus syndrome (BNS).

Fluorescence microscopy for the evaluation of elastic tissue patterns within fibrous proliferations of the skin on hematoxylin-eosin-stained slides.

BACKGROUND: Diagnosis of fibrous tumors can be challenging and expensive due to the use of special stains. OBJECTIVE: Determine the usefulness of fluorescence microscopy in the evaluation of elastic tissue patterns on hematoxylin-eosin-stained slides. METHODS: In total, 228 slides representing different fibrous tumors were evaluated for their elastic tissue patterns by fluorescence microscopy, and sensitivity and specificity were determined for relevant comparisons. RESULTS: Fluorescence microscopy was found to be useful, especially for distinguishing dermatofibroma from dermatofibrosarcoma protuberans and dermatomyofibroma from other fibrous tumors. LIMITATIONS: In some cases, excessive background staining made patterns difficult to interpret. CONCLUSION: Evaluation of elastic tissue patterns by fluorescence microscopy in fibrous tumors is a cheap and efficient means to further delineate these often challenging tumors.

Spindle cell variant of epithelioid cell histiocytoma (spindle cell histiocytoma) with ALK gene fusions: Cases series and review of the literature.

BACKGROUND: Epithelioid fibrous histiocytoma (EFH) is an uncommon dermal neoplasm expressing anaplastic lymphoma kinase (ALK) protein. Rarely a histopathological variant of this entity exhibits exclusively spindle cells. We report three cases of EFH that do not completely fulfill phenotypic criteria featuring spindle cell morphology and expressing ALK protein. We also analyze the fusion partner genes rearranged with ALK in these cases. METHODS: ALK expression and rearrangement status were evaluated by immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and next generation sequencing based gene fusion analysis. RESULTS: Three cases, all from females between 25 and 55 years old, have been biopsied from back, left arm, and thumb. All three cases showed tumor with exclusively spindle cell morphology without any epithelioid cells. The tumor cells exhibited strong ALK expression by IHC and FISH study confirmed ALK gene rearrangement in all three cases. DCTN1-ALK fusion was identified in two cases. CONCLUSION: EFH is not always purely epithelioid and its spindled cell variant, spindle cell histiocytoma, should be included in the differential diagnosis of superficial dermal spindled cell neoplasms. ALK immunostain is a useful diagnostic marker for this entity and further studies may be useful to investigate whether DCTN1-ALK fusion mutations are specific to EFH with spindled cell features.

Histopathologic features distinguishing secondary syphilis from its mimickers.

BACKGROUND: Syphilis is often misdiagnosed clinically, and biopsies might be required. OBJECTIVE: To determine histopathologic features that distinguish secondary syphilis from pityriasis lichenoides (PL), pityriasis rosea (PR), and early mycosis fungoides (MF). METHODS: Histopathologic features of 100 cases of syphilis, 110 cases of PL, 72 cases of PR, and 101 cases of MF were compared. RESULTS: Elongated rete ridges and interstitial inflammation favor syphilis over PL (likelihood ratios 3.44 and 2.72, respectively), but no feature reliably distinguishes between them. Secondary syphilis and PR can be distinguished by neutrophils in the stratum corneum, plasma cells, interface dermatitis with lymphocytes and vacuoles, and lymphocytes with ample cytoplasm. Plasma cells and lymphocytes with ample cytoplasm are rare in early MF and can be used as distinguishing features. CONCLUSIONS: Histopathologic features characteristic of syphilis can be seen in PL, PR, and early MF. Distinguishing syphilis from PL can be difficult histologically, and a high index of suspicion is required. Although elongation of rete and interstitial inflammation favor syphilis, plasma cells (historically considered a significant feature of syphilis) are often encountered in PL. Vacuolar interface dermatitis with a lymphocyte in every vacuole is considered characteristic of PL, but this feature appears to be more common in syphilis.

Scleromyxedema histopathologically mimicking hypercellular fibrous papules (angiofibomas): Case report of an unusual histopathological presentation.

Scleromyxedema (SMX) is an inflammatory condition of unknown etiology strongly associated with monoclonal gammopathy. Classical histopathology of SMX is characterized with the triad of diffuse mucin deposits, increased amount of collagen, and presence of stellate fibroblasts. Herein, we report an unusual histopathological variant of SMX in a 41-year-old female with lesions of the nose histopathologically mimicking cellular angiofibromas. The dome-shaped papules were characterized by increased collagen bundles and fascicles of spindle cells. Widened vessels were seen at the periphery of the proliferation. Cells expressed CD68. Factor XIIIa was expressed only by dendritic cells. The mucin was highlighted with colloidal iron. In sum, we draw attention to this unusual variant of SMX, which should be suspected in a setting of multiple "angiofibromas/fibrous papules" on the face with presence of mucin.

Sarcoidosis with cutaneous perineural granulomas and neurological manifestations: A potential mimicker of leprosy.

Sarcoidosis is a granulomatous condition with diverse clinical presentations, including neurological findings. It was previously hypothesized that perineural sarcoidal granulomas in the skin may be an explanation of small-fiber neuropathy. Herein, we present a case of a 55 year old female with anesthetic cutaneous lesions mimicking leprosy clinically and histopathologically and discuss the importance of this differential diagnosis.

Melanoma Ex Blue Nevus With GNA11 Mutation and BAP1 Loss: Case Report and Review of the Literature.

Cutaneous melanomas may demonstrate a variety of histopathological features and genetic abnormalities. Melanomas that arise in the setting of blue nevi, also known as "malignant blue nevus" or melanoma ex blue nevus (MBN), share a similar histopathological and mutational profile with uveal melanoma. Most uveal melanomas show characteristic GNA11 or GNAQ mutations; additional BAP1 mutation or loss is associated with the highest risk of metastasis and worst prognosis. However, the significance of BAP1 loss in melanomas ex blue nevus remains unclear. We present a case of MBN arising from the scalp of a 21-year-old woman. The diagnosis was established on histopathological findings demonstrating a markedly atypical melanocytic proliferation with increased mitotic activity, necrosis, and a focus of angiolymphatic invasion. Immunohistochemical analysis demonstrated the absence of BAP1 nuclear expression within tumor cells. Next generation sequencing detected GNA11 Q209L mutation and BAP1 loss (chromosome 3p region loss), supporting the diagnosis. We reviewed another 21 MBN cases with reported BAP1 status from the literature. MBN with BAP1 loss presented at a younger average age (41 vs. 61 years), demonstrated larger average lesion thickness (9.0 vs. 7.3 mm), and had a higher rate of metastasis (50% vs. 33%) compared with BAP1-retained MBN. BAP1 expression studies may assist in the diagnosis and management of MBN, but further research is needed.

Sweet syndrome with pulmonary involvement in a patient with myelodysplastic syndrome.

We report a patient with Sweet syndrome involving the pulmonary system in the context of myelodysplastic syndrome. Although Sweet syndrome may involve a variety of organ systems, the pulmonary system is rarely affected and can result in poor clinical outcomes, including acute respiratory distress syndrome. Both cutaneous and pulmonary symptoms respond well to systemic corticosteroid therapy and early diagnosis and treatment can improve the prognosis. Our case highlights the importance of collaboration between hematologists, dermatologists, and pulmonologists to facilitate effective diagnosis, triage, and treatment of these patients.

Infective dermatitis associated with HTLV-1 infection in a girl from Trinidad: Case report and review of literature.

Infective dermatitis (ID) associated with Human T-cell leukemia virus type-1 (HTLV-1) is a rare form of severe superinfected eczema seen mostly in the Caribbean islands and Latin America. Although rapid response to antibiotic treatment is observed, patients should be monitored for development of complications associated with this retroviral infection, including T-cell leukemia/lymphoma (ATLL) and HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). Infective dermatitis is rarely seen in the United States and therefore may be under-recognized by physicians unfamiliar with this condition. Herein, we present an additional case report of an ID associated with HTLV-1 in an 11-year-old girl from Trinidad.

Lymphocytes in Sweet syndrome: A potential diagnostic pitfall.

BACKGROUND: Patients with Sweet syndrome (SS) have acute onset of cutaneous lesions with characteristic histopathology (dense and diffuse neutrophilic infiltrate, dermal edema, leukocytoclasis and no vasculitis) accompanied by systemic symptoms. Sometimes, only skin lesions with classic histopathologic features are seen. Although SS is considered to be a "neutrophilic dermatosis," lymphocytes are also seen on histological examination. METHODS: We evaluated the cellular infiltrate in 9 biopsies from SS lesions with routine staining and immunohistochemistry. RESULTS: Lymphocytes were present in all biopsies in variable amounts, often exceeding the number of intact neutrophils. Prominent fragmentation of neutrophils rendered some biopsies "lymphocyte-rich" on routine histologic evaluation. Myeloperoxidase was helpful in highlighting the inconspicuous neutrophilic fragments in these cases. Lymphocytes were highlighted with immunohistochemistry, and had a CD3+, CD4+, CD20(-) immunophenotype, with rare CD8+ lymphocytes. CONCLUSION: Awareness of the lymphocytic component of SS is important to avoid diagnostic errors, especially in subcutaneous lesions of SS, in which the lymphocytic infiltrate predominates in the upper parts of the dermis, while the typical neutrophilic infiltrate may be seen only in the deeper dermis and subcutis. The lymphocytic component may potentially help to differentiate lesions of SS from neutrophilic urticarial dermatosis, which has not been reported to contain a significant lymphocytic population.

Folliculocystic and collagen hamartoma of tuberous sclerosis: A new case in a female patient and review of literature.

Folliculocystic and collagen hamartoma (FCCH) of tuberous sclerosis is a rare entity described in 2012 by Torrelo et al. with only 8 cases described, predominantly in males. It presents since birth or early infancy and in the majority of cases is associated with tuberous sclerosis. The hamartoma presents as an exophytic plaque and has distinctive histopathological features including hair follicles, intact or ruptured epidermal cysts, and an increased number of collagen fibers extending to the subcutaneous tissue. Herein we present an additional case of this rare entity in an 18-year-old female who met clinical criteria for tuberous sclerosis. The patient had an exophytic mass in the left temporal area for many years and wanted surgical excision due to its cosmetic appearance. Histopathology of the surgical specimen showed a hamartomatous lesion with multiple large intact epidermal cysts, hairs and increased thickened collagen. The patient has followed up for 1 year after the excision, with no recurrence. Additionally, we provide a literature review of known cases of FCCH as well as its clinical and histopathological differential diagnosis.

Cutaneous Langerhans cell histiocytosis presenting with hypopigmented lesions: Report of two cases and review of literature.

Langerhans cell histiocytosis is a rare group of disorders that results from the abnormal proliferation and accumulation of dendritic-derived cells in various organs of the body, such as the skin and bones. Hypopigmented macules are a rare cutaneous presentation of Langerhans cell histiocytosis that may pose a diagnostic dilemma when no other findings of Langerhans cell histiocytosis are present at the time of examination. We present 2 cases of the hypopigmented variant of Langerhans cell histiocytosis, including a case with histopathologic features of regression, and a review of the literature. These cases highlight the importance of including Langerhans cell histiocytosis in the differential diagnosis of an infant with hypopigmented macules and papules.

Utilization of polarized microscopy to differentiate deep penetrating nevus from equine type melanomas.

Equine type melanoma can mimic deep penetrating nevus (DPN), making histologic diagnosis challenging. We sought to investigate if the pattern of collagen polarization could be helpful in this setting. A total of 52 specimens were reviewed with polarized microscopy to determine whether refractile collagen was present within melanocytic nests vs. surrounding but not within the nests. Seven of eight (87.5%) equine type melanomas demonstrated refractile collagen within melanocytic nests in part or all of the lesion. In contrast, DPN showed no refractile collagen within the melanocytic nests. Instead, 12 (100%) DPNs and 14 of 16 (87.5%) common combined nevi (DPN plus banal nevus) demonstrated refractile collagen only surrounding melanocytic nests. The entrapment of refractile collagen, as seen with polarized microscopy, within melanocytic nests can support a diagnosis of equine type melanoma.