Erythematous lesion with peripheral purpura on the face

Signet-Ring Cell/Histiocytoid Carcinoma: Report of Two Cases and Systematic Review of the Literature on the Epidemiology, Clinical Characteristics, and Pathological and Molecular Findings

ABSTRACT

Signet-ring cell/histiocytoid carcinoma (SRCHC) is a rare appendageal tumor, mainly considering eyelids, more rarely axillae. This article describes 2 novel SRCHC cases of 71- and 66-year-old men and systematically reviews the literature on SRCHC. Of all cases reported in the literature, 73 (91.2%) were men and 7 (8.8%) were women. The median age at diagnosis was 71 years. Skin changes were located in the eyelids (68%) and axillae (32%). In all tested cases, SRCHC cells expressed CK7, CKAE1/AE3, EMA, CAM5.2, and AR and PIK3CA mutations. Future research should determine whether AR/PIK3CA-targeted therapies influence patients' survival.

Signet-ring cell/histiocytoid carcinoma of the axilla: a clinicopathological and genetic analysis of 11 cases, review of the literature, and comparison with potentially related tumours

AIMS

The aim of this study was to determine the clinicopathological and genetic characteristics of axillary signet-ring cell/histiocytoid carcinoma (SRCHC) and the relationship between axillary SRCHC, eyelid SRCHC, and conventional apocrine carcinoma (AC).

METHODS AND RESULTS

Eleven cases of axillary SRCHC, four cases of eyelid SRCHC, eight cases of axillary AC and five cases of invasive lobular carcinoma (ILC) were retrieved. Additionally, 14 axillary and 43 eyelid SRCHC cases from the literature were reviewed. Male predominance was prominent for axillary SRCHC (24:1) and eyelid SRCHC (42:5). Axillary SRCHC formed a circumscribed plaque or nodule, unlike eyelid SRCHC. Lymph node metastasis was predominantly seen in axillary SRCHC cases (72%, 18/25), but not in eyelid SRCHC cases (19%, 9/47). Axillary SRCHC and eyelid SRCHC were histopathologically similar and showed rare tubular formations. Immunoexpression of cytokeratin 7, cytokeratin 19, mucin 1, mucin 5AC, BerEP4 and androgen receptor was seen in all tested cases of the four diseases. Oestrogen and progesterone receptors were negative in both types of SRCHC and AC, but were strongly positive in ILCs. Complete loss of E-cadherin expression was seen in approximately one-quarter of both types of SRCHC and in all ILCs. PIK3CA mutations were detected in all three sequenced cases (two axillary SRCHCs and one eyelid SRCHC).

CONCLUSION

The histopathological, immunohistochemical and genetic findings suggest that both types of SRCHC are phenotypic variants of AC, although there are differences in sex, macroscopic findings and the frequency of lymph node metastasis among the three. In contrast, ILC differs from the other three tumour types.