Miliarial type primary cutaneous follicle center lymphoma

Miliaria-like primary cutaneous B-cell lymphoma is a very rare variant of primary cutaneous B-cell lymphoma (PCBCL) that manifests as asymptomatic, reddish or skin-colored, small papular surface-smooth elevations that may clinically resemble miliaria in a broader sense.

Mean age (52 years in one review - Massone C et al. 2011)

Face, neck, ears

Dense nodular or diffuse infiltration of the dermis and subcutis. Clear orientation to the adnexal structures with subepidermal free zone (free border zone). No epidermotropy. A clear follicular pattern is observed especially when localized on the head. Cytomorphologically, there are smaller cells with clearly notched nuclei and numerous granules (characteristics of centrocytes) as well as larger cells with large round nuclei and one or more prominent nucleoli (characteristics of centroblasts). The infiltrate is supplemented by immunoblasts (large nuclei with a central nucleolus), small lymphocytes, histiocytes, rarely eosinophilic granulocytes and plasma cells. Numerous reactive T cells are found, especially in early lesions.

As the tumor progresses, follicular structures are expressed less frequently and the number of reactive T cells is relatively reduced. Monomorphic populations of large germinal center cells tend to predominate.

Immunohistology: Expression of B-cell associated antigens: CD19, CD20, CD79a. In follicular structures: expression of CD10; also BCL6, CD21 (dendritic reticulum cells).

PCR: in about 70% of cases detection of the clonal tumor cell population with monoclonal rearrangement of the genes for the immunoglobulin heavy chain.

The cytogenetic feature of systemic follicular lymphoma is the chromosomal translocation t(14;18) (q32;q21) in up to 90% of cases. This translocation is only found in a minority of primary cutaneous follicular lymphomas (!). The chromosomal translocation leads to overexpression of Bcl-2, an anti-apoptotic oncogene.

The diagnosis requires histologic, immunohistologic and molecular analyses based on the very characteristic clinical picture (chronic, small nodular, grouped, surface smooth, asymptomatic).

Rosacea

Lupus miliaris disseminatus faciei

persistent arthropod prick reactions

Miliaria-like reactive B-cell proliferation

Can be indolent, but can also take an aggressive form.

1. Massone C et al. (2011) Miliary and agminated-type primary cutaneous follicle center lymphoma: report of 18 cases. J Am Acad Dermatol 65:749-755.
2. Moulonguet I et al. (2012) Miliary-type perifollicular B-cell pseudolymphoma (lymphocytoma cutis): a misleading eruption in two women. J Cutan Pathol 39:1016-1021
3. Villalobos-Ayala RA et al. (2022) Lymphocytoma cutis (cutaneous B-cell pseudolymphoma): study of 102 cases with emphasis on the histological characteristics and immunohistochemistry of the miliarial type. Int J Dermatol 61:316-323.
4. Willemze R et al. (2005).WHO-EORTC classification for cutaneous lymphomas. Blood 105:3768-3785