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 Langerhans Cell Histiocytosis as Presenting Sign of Systemic B-Cell Lymphoma.

ABSTRACT: Langerhans cell histiocytosis (LCH) is a rare clonal proliferative disorder most commonly involving the bone and skin; however, it can arise in many other locations. It is predominantly a pediatric disease, but adult cases occur. Here, we present a case of adult-onset cutaneous LCH with systemic symptoms, believed to represent disseminated LCH. Further evaluation, however, revealed concomitant bone marrow involvement by a small B-cell lymphoma. An association between B-cell lymphoma and cutaneous LCH has only rarely been previously reported. This report adds to the growing body of literature, however, on associations of cutaneous LCH with hematologic malignancies, and it illustrates the need for a complete systemic evaluation including a bone marrow biopsy in suspected cases of disseminated LCH.

Ileostomy adenocarcinoma in Crohn's disease.

PURPOSE: Adenocarcinoma of an ileostomy is rare with less than 50 reported cases in the literature. Ileostomy adenocarcinoma in Crohn's disease is even more rare, with only 4 reported cases. We present a case of ileostomy adenocarcinoma with lymph node metastasis occurring 51 years after proctocolectomy and Brooke ileostomy in a female with Crohn's disease. This case represents the longest documented interval between Brooke ileostomy and ileostomy adenocarcinoma diagnosis and summarizes clinical signs that warrant biopsy of a peristomal plaque to differentiate adenocarcinoma from clinical mimics such as pyoderma gangrenosum (PG). METHODS: Clinical, histological, and surgical patient data were reviewed. A literature review of adenocarcinoma arising from ileostomy sites was performed. RESULTS: We report a case of a 67-year-old woman that presented with a peristomal skin lesion developing over 10 years. After multidisciplinary discussion between gastroenterology, colorectal surgery, and dermatology, ileoscopy revealed moderately differentiated, invasive adenocarcinoma arising from the ileostomy site. Wide surgical excision and en bloc resection of the peristomal lesions were performed, and the final pathology revealed lymph node metastasis. The patient is currently undergoing adjuvant chemotherapy. CONCLUSIONS: Clinicians should maintain a high level of suspicion when ileostomy patients develop a peristomal lesion.

A Novel Spindle Cell Population in a Case of Primary Osteoma Cutis With GNAS Mutation.

Primary osteoma cutis is a rare condition belonging to a spectrum of related genetic disorders, including progressive osseous heteroplasia, plate-like osteoma cutis, and Albright hereditary osteodystrophy, which share identical histologies with cutaneous intramembranous ossification and mutations in GNAS. We report a case of a 15-week-old girl who presented with an enlarging, indurated subcutaneous lesion on her right flank. CT scan showed an extensive subcutaneous sheet of calcification. Histologic evaluation revealed heterotopic calcification and intramembranous ossification within the dermis and mature bone largely replacing the subcutaneous fat compatible with osteoma cutis. Molecular testing was performed and identified an inactivating GNAS mutation. Unique to this case is a dermal proliferation of bland spindle cells that blended with deposited osteoid material. This has not been reported in association with primary osteoma cutis previously. These spindle cells were positive for CD44, Bcl-2, muscle-specific actin, and smooth muscle actin while negative for CD34. We hypothesize that these cells are immature mesenchymal cells, representing an early cellular phase of ossification. We favor these cells provide the background in which ossification is occurring, supporting the theory of osteoblastic metaplasia in the etiology of this condition.

CD5+ Primary Cutaneous Diffuse Large B-Cell Lymphoma, Leg Type, Presenting as an Asymptomatic Nodule.

Primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT), is a rare and aggressive variant of primary cutaneous lymphoma that typically expresses B cells as well as MUM1/IRF4, BCL2, and FOXP1, whereas BCL6 may be present or undetectable. We present a case of CD5+ PCDLBCL-LT presenting as a 6 mm pink-bluish nodule on the mid-left thigh, which was concerning for basal cell carcinoma. The histological examination reveals the presence of an intradermal proliferation of large, atypical CD5+, CD20+ BCL2+, BCL6+, MUM-1+, and Cyclin-D1+ lymphocytes in a nodular, diffuse interstitial and perivascular distribution. Because the patient presented with a small, single nodule, the systemic treatment of multiagent chemotherapy was avoided and localized electron beam radiation therapy with rituximab was initiated instead, achieving complete response. Early identification of PCDLBCL-LT is key for maximal therapeutic benefit and prognosis; it is important to consider PCDLBCL-LT on the differential when evaluating small, single nodules on the lower extremities of elderly patients.

Educational Case: Malignant Melanoma.

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, see http://journals.sagepub.com/doi/10.1177/2374289517715040.1.

Extranodal Marginal Zone Lymphoma of the Lung: Evolution from an Underlying Reactive Lymphoproliferative Disorder.

Extranodal Marginal Zone Lymphoma (ENMZL) of Mucosa-Associated Lymphoid Tissue (MALT) is a problematic and sometimes controversial diagnosis. While commonly seen in the stomach in the setting of chronic Helicobacter pylori infection, other extranodal sites, such as the lung, may also present with disease. ENMZL is clinically and morphologically heterogeneous; however, regardless of presentation, the etiology lies in the accumulation of lymphoid tissue in non-traditional sites. This phenomenon is typically secondary to an underlying inflammatory stimulus such as chronic infection or autoimmune states. The current case report details the clinical history of a patient with Sjögren syndrome over a four year period who eventually developed ENMZL. The patient initially presented with an atypical, but polyclonal, lymphoproliferative process diagnosed as lymphocytic interstitial pneumonia. Over time, the patient showed evolution to a monoclonal process with associated radiologic progression of disease. This evolution manifested as a dense lymphoid infiltrate with prominent plasmacytic differentiation and the development of a lung mass radiologically. This case contributes to the growing body of knowledge that suggests ENMZL lies along a biological spectrum of lymphoproliferative disorders whereby a benign, reactive process may eventually undergo malignant transformation. This evolution likely represents the acquisition of genetic abnormalities that allow autonomous proliferation in the absence of the initial immune stimulus. In practice, determining when this event occurs and, thus, distinguishing between reactive and neoplastic disorders within this spectrum may be difficult as no single clinicopathologic feature may be present to establish the diagnosis. This case further illustrates the importance of correlating the clinical, radiologic and pathologic data to evaluate patients with atypical pulmonary lymphoproliferative disorders and to allow the optimal management of their disease.