Intralymphatic histiocytosis is a rare condition characterized by the presence of dilated lymphatic vessels containing aggregates of mononuclear histiocytes (macrophages) within their lumina. The phenomenon seems to occur almost exclusively within the reticular dermis. Although its pathogenesis remains uncertain, there has been speculation about the possible relationship between intralymphatic histiocytosis and intravascular reactive angioendotheliomatosis. In addition, several examples historically have been associated with rheumatoid arthritis. We describe our experience with 16 cases of intralymphatic histiocytosis. Clinically, the lesions were located predominantly on the upper and lower limbs, and they consisted of asymptomatic and poorly demarcated erythematous plaques and livedo reticularis-like lesions. They were characterized histopathologically by dilated vascular structures involving the reticular dermis. Some of these dilated vessels had empty lumina, whereas others contained variable number of mononuclear histiocytes. An inflammatory response of variable intensity from case to case was also present in the adjacent dermis. The dilated vessels exhibited thin walls with irregular shapes, and a single discontinuous layer of flat endothelial cells lined their lumina. Immunohistochemically, the endothelial cells lining the dilated lumina expressed immunoreactivity for CD31, CD34, podoplanin, D2-40, Lyve-1, and Prox-1, which confirmed their nature as lymphatic endothelial cells. Intralymphatic mononuclear histiocytes expressed CD68 (PGM1), although some cases also had variable immunoexpression for myeloperoxidase, CD31, and podoplanin. In the 4 cases that employed double immunohistochemistry, with podoplanin + CD68 (PGM1) or with Lyve-1 + CD68 (PGM1), each marker highlighted their specific target cells unequivocally; the endothelial cells expressed podoplanin or Lyve-1 immunoreactivity, and intralymphatic histiocytes showed CD68 (PGM1) immunoexpression. Our findings expand on the previously described morphologic and immunohistochemical features of intravascular histiocytosis. We also discuss the possible relationship between intralymphatic histiocytosis and the so-called reactive intravascular angioendotheliomatosis.

To ascertain and clarify the effectiveness and advantages of the geometric staged excision technique for the removal of lentigo maligna (LM) and lentigo maligna melanoma (LMM).Design: This was a retrospective review of a patient database composed of 293 cases of LM and LMM.Setting: The Laser and Dermatologic Surgery Center in St Louis, Missouri, an academic-affiliated, private dermatologic surgery center.Patients: All patients with a diagnosis of LM and LMM treated by staged excision from 1999 to 2007. Main Outcome Measures:The overall rate of recrudescence, margins required for clearance, stages re-quired for clearance, and lesional characteristics were examined.Results: The rate of recrudescence after geometric staged excision was 1.7% (4/239), with a mean of 32.3 months of follow-up. The mean margin to clearance after excision was 6.6 mm for LM and 8.2 mm for LMM. A total of 11.7% of LMM was initially diagnosed as LM on biopsy, with the invasive component discovered during the excision.Conclusions: Geometric staged excision is an optimal method of removal of LM and LMM given its low rate of recrudescence and ability for complete examination of the peripheral and deep margins of the specimens.

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Cornoid lamellation is a specific disorder of epidermal maturation manifested by a vertical "column" of parakeratosis and is the hallmark of porokeratosis. The cornoid lamella is characterized by a ridgelike parakeratosis. We present 11 patients with solitary lesions of a distinct pattern of cornoid lamellation. The mean age at presentation clinically was 57 years; there were 9 men and 2 women. The duration of the lesions ranged from 3 months to 5 years (mean of 23 mo). All lesions were solitary, distributed mainly on the distal upper and lower limbs, and were clinically described as hyperkeratotic plaques or nodules; some were verrucous. Histologic examination showed a well-defined lesion characterized by acanthosis and verrucous hyperplasia with prominent multiple and confluent cornoid lamellae. No additional lesions were identified in any patient, with a mean follow-up duration of 34 months. No personal or family history of porokeratosis was elicited and no immunosuppressive conditions were noted. These lesions with multiple and confluent cornoid lamellae represent benign acanthomas with features of porokeratosis. As a solitary tumorlike lesion, it is akin to warty dyskeratoma and epidermolytic acanthoma, thus we have coined the term porokeratoma.

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