Follicular mucinosis (FM) is defined as the accumulation of a mucinous material within the hair follicle. Since its first description by Pinkus1 in 1957 in the setting of alopecia mucinosa, 2 main forms have been classically recognized: a benign idiopathic form, primary follicular mucinosis (PFM), which usually appears in young adults and regresses spontaneously; and a secondary form, lymphoma-associated follicular mucinosis (LAFM),2 which mostly occurs in elderly patients. Most cases of LAFM are related to cutaneous T-cell lymphomas (especially mycosis fungoides), although some cases of Hodgkin disease3 and chronic lymphocytic leukemia4 have also been reported.
A man in his 60s initially presented with a history of an intermittently pruritic eruption on the chest and proximal limbs. Two skin biopsies were performed on the neck and the back. The lesions were reported as primary, cutaneous, low-grade, B-cell lymphoma favoring marginal B-cell lymphoma. The peripheral blood sample test results and the bone-marrow core biopsy findings were normal. Computed tomographic scans did not reveal any abnormality. The patient was never treated and did not come back because the lesions disappeared spontaneously. Eight years later, he presented with multiple, millimetric, pruritic, skin-colored papules with a follicular pattern on the chest, back, and upper extremities (Figure 1). He did not have any constitutional symptoms.
Multiple, diffuse, pruritic, skin-colored papules show a follicular pattern on the chest.
Two biopsies performed on the chest and the abdomen revealed dense lymphocytic infiltrate in the reticular dermis, centered around and within hair follicles, which showed cavities filled with abundant mucinous material (Figure 2A). Small and irregular lymphocytes were admixed with large lymphocytes, plasma cells, and eosinophils. Atypical cells expressed CD20, CD43, CD79α and BCL6. Some intraepithelial lymphocytes tested positive for CD3 and CD4, but most of them expressed CD20 (Figure 2B). Polymerase chain reaction revealed a monoclonal rearrangement of the heavy chain immunoglobulin IgH gene with a peak at 160 base pairs. A reactive lymphoid T cell (CD3, CD43 and CD4 positive) infiltrate was found surrounding the neoplastic cells.
A, High-magnification image showing follicular mucinosis and follicular tropism of the atypical lymphocytes (hematoxylin-eosin, original magnification ×100). B, Dense CD20+ lymphoid proliferation around and within the pilosebaceous unit (CD20 staining, original magnification ×100).
The patient was finally diagnosed as having primary cutaneous follicle center lymphoma associated with follicular mucinosis. At last follow-up 4 months later, the lesions and the pruritus were slowly improving, although they had not completely disappeared.
In 1995, Benchikhi et al4 reported the first case of cutaneous B-cell lymphoma associated with follicular mucinosis in a patient with bone-marrow and peripheral blood infiltration.4 We report the first case of primary cutaneous follicle center lymphoma with follicular mucinosis.
Cutaneous lymphomas can usually be distinguished by architectural features, where most atypical lichenoid infiltrates implicate cutaneous T-cell lymphoma, especially when areas of epidermotropism are present; cutaneous B-cell lymphomas often appear with a nodular to diffuse lymphoid infiltrate and relative sparing of the epidermis. However, B-cell lymphomas can sometimes show atypical lymphoid infiltrates mainly limited to the papillary dermis, epidermotropism, interstitial involvement, and absence of grenz zone, mimicking mycosis fungoides.5,6 To date, at least 3 cases have been reported of epidermotropic marginal zone B-cell lymphoma.6 Immunohistochemical studies demonstrating B-cell phenotype (CD20, and CD79α positivity) with marginal zone differentiation (BCL2 positivity, and BCL6, CD10 and CD5 negativity) for the epidermotropic cells, as well as the majority of the dermal cells, confirmed the diagnosis in these cases. In our case, the tumor cells tested diffusely positive for BCL-6, which rather suggested a follicular center differentiation.
In summary, our case represents the first case to our knowledge of primary cutaneous follicle center lymphoma with follicular mucinosis and a very unusual miliary clinical presentation. Morphologic findings, often used to distinguish among different types of cutaneous lymphomas, can sometimes be misleading, and molecular characterization is important to support the diagnosis.
Corresponding Author: Jose Luis Rodriguez-Peralto, MD, PhD, Dpto de Anatomía Patológica, Hospital Universitario12 de Octubre, Avda de Córdoba s/n, 28041 Madrid, Spain (firstname.lastname@example.org).
Published Online: June 18, 2014. doi:10.1001/jamadermatol.2013.9060.
Conflict of Interest Disclosures: None reported.
Additional Contributions: We thank Yolanda Ruano, PhD, Department of Pathology, and Concepcion Postigo, MD, and Pablo Ortiz, MD, Department of Dermatology, Hospital Universitario 12 de Octubre, Universidad Complutense, Instituto de Investigación I+12, Madrid, Spain, for their contributions to the final diagnosis in this case. They received no compensation for their contributions beyond that paid in the normal course of their employment.
Garrido MC, Riveiro-Falkenbach E, Rodriguez-Peralto JL. Primary Cutaneous Follicle Center Lymphoma With Follicular Mucinosis. JAMA Dermatol. 2014;150(8):906-907. doi:10.1001/jamadermatol.2013.9060