Generalized multinucleate cell angiohistiocytomas and thoughts on diagnostic first impressions
April 1, 2017
I became aware of multinucleate cell angiohistiocytomas (MCA) when I learned of an article published by friends who reported the first cases in the United States (1). The following abstract by Smolle et al (2) accurately described the entity, and my concept of MCA has remained fixed for nearly 3 decades:
The term ‘multinucleate cell angiohistiocytoma’ was first introduced by Smith and Wilson Jones in 1985. We report the clinicopathological, immunohistological and ultrastructural findings observed in two patients. Multinucleate cell angiohistiocytoma occurs mainly in middle-aged women and is usually located at acral sites, particularly the distal extremities. Grouped, brown-red, slightly elevated, asymptomatic papules slowly develop over several months until further growth ceases. There is no evidence of systemic disease. Histologically, the dermis shows numerous well developed capillaries with prominent endothelia, large bizarre basophilic and often multinucleate cells with a sparse lymphohistiocytic infiltrate. The immunohistological and ultrastructural findings suggest a fibroblastic differentiation of the large multinucleate cells.
My perception of MCA has now been expanded to include generalized MCA (GMCA), as reviewed by Wang et al (3). Twelve cases (including the index case report) were reviewed. Compared to the original description, patients were younger with an equal male: female ratio. The number of lesions ranged from the “tens” to the “hundreds”, on the trunk and extremities, with a duration ranging from 6 months to > 20 years. Although 3 patients had associated autoimmune diseases, this was felt to be coincidental, as the remaining 9 patients had no associated disorders. No known triggering factors existed. GMCA are considered reactive rather than neoplastic lesions. Immunohistochemistry demonstrates variable CD68 staining and positive endothelial markers (CD34, CD31, and Factor VIII-related antigen). Lesions need not be treated — if removal is desired, either excisional surgery or laser ablation may be utilized. GMCA should be differentiated from generalized eruptive histiocytomas, eruptive leiomyomas, dermatofibromas, lymphomatoid papulosis, microvenular hemaangiomas, Kaposi sarcoma, and leukemia cutis. Histologically, lesions most resemble fibrous papules.
If faced with a patient with multiple red-brown papules on the trunk and extremities, I never would have considered the diagnosis of GMCA, because it did not fit my preconceived, mentally imprinted concept of the disease. Although little is known about how first impressions are encoded in memory, research suggests that the neural underpinnings of first impressions involve the dorsal medial prefrontal cortex (4). What if the initial description of MCA was GMCA? Would the diagnosis be considered for middle-aged women with a few acral lesions (“classical” MCA)? We all learn by imprinted pattern recognition that provides a frame of reference. It is humbling to think how askew those reference points may be, with misdiagnosis as a result. First impressions are important, as long as we remember that perhaps they should be modified periodically.
1. Shapiro PE, et al. Multinucleate cell angiohistiocytoma: A distinct entity diagnosable by clinical and histologic features. J Am Acad Dermatol 1994; 30: 417-22.
2. Smolle J, et al. Multinucleate cell angiohistiocytoma; A clinicopathological, immunohistochemical and ultrastructural study. 1989; 121: 113-21.
3. Wang M, et al. Generalized multinucleate cell angiohistiocytoma: Case report and literature review. J Cutan Pathol 2017; 44: 125-34.
4. Gilron R, Gutchess AH. Remembering first impressions: Effects of intentionality and diagnosticity on subsequent memory. Cogn Affect Behav Neurosci 2012; 12: 85-98.
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