Abnormal T-lymphocytes in lymphomatoid papulosis: A cytomorphological study with a reconstruction of a major part of the cell differentiation cycle

Eosinophilic histiocytosis. Histopathology and immunohistochemistry

We review the clinical features, histopathology, and immunohistochemistry in three cases of eosinophilic histiocytosis, comparing lymphomatoid papulosis and eosinophilic histiocytosis. Each of the patients presented with self-healing recurrent papules and ulcerative nodules that were associated with pruritus. Disease duration was 5 months to 9 years. Histologically, the lesions demonstrated spongiosis and lymphocytic exocytosis, epidermal hyperplasia, papillary dermal edema, and a superficial and deep mixed perivascular inflammatory infiltrate. The infiltrate showed numerous eosinophils, histiocytoid cells, lymphocytes, and large mononuclear cells with atypical hyperchromatic nuclei. Most of the lymphocytes and large mononuclear cells with atypical nuclei marked with UCHL-1 (T-cell marker). The histiocytoid cells marked with S-100 and were dendritic both in the epidermis and the dermis. Eosinophilic histiocytosis appears to differ from classic lymphomatoid papulosis. It presents with recurrent papules and nodules associated with marked pruritus. Eosinophilic histiocytosis uniformly has more eosinophils and does not have the Reed-Sternberg cells often observed in lymphomatoid papulosis type A. Eosinophilic histiocytosis does not have cells that mark with Ki-1 and shows numerous S-100-positive histiocytoid cells that are most likely Langerhans cells, unlike lymphomatoid papulosis. However, eosinophilic histiocytosis may be an unusual Ki-1-negative variant of lymphomatoid papulosis with histopathologic changes not typical of type A or type B. In addition, eosinophilic histiocytosis lacks multinucleated histiocytes and the atypical histiocyte with a reniform nucleus, findings that are characteristic of histiocytosis X. Further studies are needed to define the pathophysiology and prognosis of this apparently distinct entity more accurately.

Lymphomatoid papulosis: a clinical and histopathologic review of 53 cases with leukocyte immunophenotyping, DNA flow cytometry, and T-cell receptor gene rearrangement studies

BACKGROUND

Lymphomatoid papulosis (LyP) is a recurrent hemorrhagic papular skin eruption with a clinically benign course and histopathologic features of lymphoma.

OBJECTIVE AND METHODS

To better characterize this disease, we studied 53 patients seen since 1965.

RESULTS

A lymphoproliferative malignancy developed within 2 to 36 years after onset of LyP in eight patients. Histologically, the dermis in LyP showed an infiltrate of large (type A) or small (type B) atypical lymphocytes. The large atypical cells (type A) stained with CD30 (Ber-H2). Seven of the patients in whom lymphoma developed had type A histologic features. DNA flow cytometry showed mainly a diploid pattern, except for two cases that showed aneuploidy. Five of 11 patients showed T-cell receptor (TCR) clonal gene rearrangements; lymphoma has not developed in these patients. One patient had a TCR rearrangement in a plaque of mycosis fungoides but not in the LyP lesion.

CONCLUSION

LyP is either a reactive skin condition or a localized lymphoid malignancy. Neither DNA flow cytometry nor TCR gene rearrangement can predict the 15% to 19% of patients in whom a lymphoma will develop. Continued observation of all patients is essential.

Immunophenotypic and genotypic characterization of lymphomatoid papulosis

BACKGROUND

Lymphomatoid papulosis (LyP) is a chronic dermatosis that histologically resembles malignant lymphoma. Thus far, only a few cases of LyP have been characterized in detail with regard to immunophenotype, genotype, and karyotype.

OBJECTIVE

Our purpose was to study seven patients with LyP and compare the results to those reported in the literature.

METHODS

Skin biopsy specimens were analyzed by frozen section immunohistochemical and molecular biologic techniques. Cytogenetic analysis was also performed in three cases.

RESULTS

The atypical lymphoid cells consisted of activated helper T cells; four of the seven patients had lesions with a detectable clonal T-cell population. A peripheral T-cell lymphoma developed in one patient before the emergence of a genotypically different LyP T-cell clone. Cytogenetic studies were abnormal in one case of LyP and normal in another, whereas the karyotype of the lymphoma was abnormal.

CONCLUSION

LyP is a preneoplastic proliferation of activated helper T cells, which is often clonal and may regress and expand with the development of new LyP clones or lymphoma.