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Lichen myxedematosus is a chronic cutaneous mucinosis that can present on a spectrum from localized cutaneous lesions to systemic disease of scleromyxedema. The clinical presentation of localized cutaneous lichen myxedematosus is waxy lichenoid papules, nodules, and/or plaques that have histopathologic findings of mucin deposition and a variable degree of fibroblast proliferation. There is an absence of serum paraproteins, and there are no other systemic causes of cutaneous mucinosis such as thyroid disease. The pathogenesis of lichen myxedematosus is unknown. We report 3 cases of localized cutaneous lichen myxedematosus with a light chain-restricted plasmacytic component by in situ hybridization. Our findings deliver an insight for disease pathogenesis and highlight for the first time, the significance of plasma cells in lesions of localized cutaneous lichen myxedematosus. We suggest that plasma cell light chain restriction could represent a clue to distinguish localized cutaneous disease from systemic disease.

A 46-year-old white male with a history of HIV (CD4 245), acquired epidermodysplasia verruciformis, anal carcinoma in situ, hepatitis B and C presented with 3 asymptomatic, nontender, firm pink/skin-colored nodules involving the arm, left lateral leg, and right third finger. One year later, he developed a similar lesion on his right medial lower leg. Excisional biopsy of one of the lesions showed an atypical spindle cell neoplasm of the dermis compatible with a low-grade sarcoma of fibroblastic origin. Testing for human herpes virus-8, 23 human papillomavirus types, Epstein-Barr virus, and FUS fusion protein were negative. The patient underwent diagnostic imaging with computed tomography scans of the chest, abdomen, and pelvis along with positron emission tomography scan to ensure that there was no other occult primary tumor, all of which were negative. The lesions were excised and have not recurred with 3 years of follow-up. The best histopathologic term for these lesions is multiple low-grade sarcomas of fibroblastic phenotype. They have been proven to be nonaggressive, with little or no metastatic potential. This is a neoplastic process that has not been well defined in the literature. To our knowledge, there are no previous reports of these lesions occurring in multiple sites or in an HIV-positive patient.

Melanoma cell migration along the outside of vessels has been termed "extravascular migratory metastasis" (EVMM), as distinct from intravascular dissemination. Previous studies in both human and experimental melanoma models have shown angiotropism of melanoma cells, suggesting EVMM. Our objectives are to study the mechanism of dissemination of human melanoma cells in the chick chorioallantoic membrane (CAM) and to compare the histopathology in the CAM with that of patients with in transit and other cutaneous melanoma metastases. Human and murine melanoma cells were inoculated onto the CAM and observed over a 10-day period for tumor dissemination. Both human melanoma specimens from 26 patients and melanoma cells growing on the CAM showed the presence of tumor cell angiotropism at the invasive front of the tumor and at some distance from the tumor mass. In addition, a clear progression of melanoma cells spreading on the CAM was observed along the abluminal surface of vessels, where they occupied a perivascular location. By day 10 after injection, small micrometastases had developed along vessels, in a pattern similar to that in transit and other cutaneous melanoma metastases. In addition, the results suggested that the number of micrometastases directly correlated with increasing tumor volume. Taken together, these data suggest that the CAM is a relevant model for studying tumor cell dissemination, and that EVMM may be a mechanism by which some melanoma cells spread to nearby and even distant sites.

Background. Acroangiodermatitis is a benign vesicular process encountered on the lower extremities that histologically resembles the superficial form of stasis dermatitis, but is clinically characterized by circumscribed violaceous, brown or dusky macules, papules, or plaques. Furthermore, unlike stasis dermatitis, acroangiodermatitis is usually associated with minimal epidermal changes and eosinophils in the inflammatory infiltrate in the dermis. Kaposi's sarcoma, pigmented purpura, vasculitis, and lichen planus are other conditions that should be considered when making a diagnosis of acroangiodermatitis. Methods. Ten patients with acroangiodermatitis were referred to us by area physicians. Hematoxylin and eosin, periodic acid-Schiff, Pearl's (an iron stain), and an immunoperoxidase stain for Factor VIII were performed on routinely embedded paraffin sections. Results. All cases showed new vessel proliferation, perivascular inflammation of superficial and mid-dermis, consisting of lymphocytes, histiocytes, eosinophils, occasional plasma cells, extravasation of red blood cells, and hemosiderin pigment deposition. Dermal fibrosis was observed in all cases. None of the patients showed changes of vasculitis or Kaposi's sarcoma. Only one patient displayed significant epidermal changes of spongiosis and mild acanthosis. Conclusions. Acroangiodermatitis is an uncommon entity with peculiar clinical and histologic features and should be confirmed by histologic tests.

REPORT OF A CASE A 57-year-old woman presented with a 4-day history of a painful ulcerative erythematous lesion on the medial aspect of her right upper thigh. She denied any associated fever, chills, recent trauma, or bites but reported working in her garden several times in the few weeks before the onset of the lesions. Her history was significant for diet-controlled non—insulin-dependent diabetes and idiopathic cutaneous leukocytoclastic vasculitis that responded well to a short course of prednisone 3 years earlier. She received no medications since then. The physical examination showed her to be afebrile. On the aforementioned thigh was a moderately tender bullous lesion (2.2×3.5 cm). The lesion displayed central necrosis, early ulceration, and surrounding bluishred erythema and induration (diameter, 6 to 7 cm)( Figure 1 ). Two crusted pustular lesions (4 to 5 mm) with surrounding erythema were noted on her left upper arm. There was no palpable adenopathy. The