In all cases, imaging studies revealed a solitary osteolytic or osteodense mass in the bone underneath the cutaneous lesion except for one case, in which the mass was present, but distant from the skin lesion. In a few patients, the bone mass was palpable underneath the cutaneous lesion. In most instances, it was located on a rib or the sternum; in other cases, it was located on the skull, scapula, or clavicle. The histological analysis of these excised bone masses was consistent with a plasmacytoma by immunohistochemical demonstration of either the monotypic kappa (κ) or lambda (λ) immunoglobulin light chains.
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2Skin biopsies taken from the cutaneous patch overlying the plasmacytoma revealed a benign-appearing dermal vascular hyperplasia with increased surrounding dermal mucin.
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6 Some cases also featured a perivascular inflammatory dermal infiltrate mainly consisting of lymphocytes, neutrophils, and macrophages ().
1 Immunohistochemical staining, carried out in some instances, did demonstrate λ chain deposition, mainly around the dermal blood vessels.
2 One case showed increased fibrosis in the deep dermis and hypodermis. The epidermis was mostly spared; only one case featured mild epidermal spongiosis and exocytosis.
1Histopathological examination of the excised lymph nodes revealed either nonspecific findings (such as hyperplasia of native lymphocytes and sinusoidal lymphoplasmacytosis) or, in two of the patients, histological findings consistent with Castleman’s disease, a condition known to be associated with POEMS syndrome.
6 The classic histological findings of Castleman’s disease consist of follicular lymphoid hyperplasia, possibly exhibiting germinal centers, along with significant proliferation of the capillaries and hyperplasia of the endothelial cells.
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9Other laboratory findings worth mentioning include a monoclonal spike in serum electrophoresis, Bence Jones proteinuria, and hypercellularity and hyperproteinemia of the cerebrospinal fluid. However, none of the patients met the criteria for a diagnosis of multiple myeloma. When performed, laboratory testing for
Borrelia burgdorferi proved unrevealing.
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2 Electromyographic studies confirmed the presence of axono-myelinic motor and sensory neuropathy.
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