ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 Detection of clonal T cell receptor gamma gene rearrangements in mycosis fungoïdes S. Ben Cheikh, R. Jouini, S. Klai, F. Khanchel, I. Helal, K. Ben Lazreg*, R. Hedhli, E. Ben Brahim, H. Hammami, S. Fenniche, A. Chadli *Habib Thameur Hospital Pathology Department, Tunisia Background & objectives: The diagnosis of Mycosis Fongoides (MF), especially early MF, is challenging. It might be difficult to distinguish it from inflammatory disorders. Monoclonal rearrangement can be help- ful. The aim of the study was to describe molecular aspects of MF. Methods: We conducted a retrospective study that included all cases of MF confirmed by histopathological and immunohistochemical (IHC) examination in the Pathology Department in collaboration with the Dermatology Department at Habib Thameur Hospital of Tunisia from 2008 to 2020. Genomic DNA was extracted from lesional tissues and rearrangements of TCR-gamma chain gene were amplified using the IdentiClone polymerase chain reaction (PCR). Results: We enrolled 56 patients. The mean age at diagnosis was 51.8 years (15 - 83 years) with a male to female ratio of 1.94. Cases were: 35 classic MF, 12 pilotrope MF, five CD8-positive MF, three granulomatous MF and one hypopigmented MF. The rearrange- ment of the TCR- ϒ was performed in 30 cases. It was monoclo- nal in 18/30 cases (60%) and polyclonal in 12 cases (40%). At an early stage, monoclonality was present in 6/13 cases (46%) and polyclonality in 7/13 cases (54%). Polyclonality was found in 11 biopsies (73%) dating back more than 5 years, with a statistically significant association between clonality and the year the sample was received (p=0.05). Conclusion: The detection of clonal TCR rearrangement can be helpful in establishing the diagnosis of MF. In fact, the Interna- tional Society for Cutaneous Lymphomas (ISCL) and the European Organization of Research and Treatment of Cancer (EORTC) sup- port a diagnostic algorithm for early MF which includes TCR gene rearrangement analysis. However, some benign and reactive inflam- matory lesions may also have clonal rearrangement. As a result, MF diagnosis should be based on confrontation of clinical, histological, immunohistochemical, and molecular data. PS-12-014 Histopathologic features of mycosis fungoides: a morphologic study on 134 biopsy specimens from 56 patients S. Ben Cheikh, R. Jouini, I. Helal, F. Khanchel, K. Ben Lazreg*, R. Hedhli, O. Khayat, H. Hammami, S. Fenniche, E. Ben Brahim, A. Chadli *Habib Thameur Hospital Pathology Department, Tunisia Background & objectives: The diagnosis of mycosis fungoides (MF) is very challenging especially at early stage. The aim of this study was to describe histologic and immunohistochemical presentations of MF. Methods: We retrospectively reviewed 134 biopsies from 56 patients with documented MF in patch, plaque and tumour stages. Results: A total of 134 biopsies from 56 patients were reviewed. The 43 cases of early MF showed epidermotropism in 42 biop- sies (98%), pilotropism in 37/38 (97%) and syringotropism in 25/39 (64%). Lymphocytic dermal infiltrate was superficial and perivascular in 22/43 biopsies (51%). Necrotic keratinocytes were noted in 3/43 biopsies (9%). Band-like lymphocytic infiltrate of superficial dermis was seen in 30 biopsies (56.6%) at plaque stage and was extended to the entire dermis in 36 biopsies (26.9%) at tumour stage. Fibrosis of papillary dermis was observed in 90 biopsies (67.2%). At immunohistochemistry, 129 biopsies (96.3%) demonstrated CD3+, CD4+ and CD8- phenotype and lack of CD7 expression was observed in 17/22 biopsies. Conclusion: The histologic diagnosis of MF especially at early stage is one of the most vexing problems in dermatopathology, because the histopathologic features may simulate a variety of inflammatory skin disorders. Immunohistochemistry can help in diagnosis in some cases. Hower, clinicopathological correlation remains the “gold standard” for making an accurate diagnosis. PS-12-015 Immunohistochemical staining for p16 is a useful adjunctive test in the diagnosis of Bowen’s disease F. Khanchel, S. Elfekih*, H. Hammami, I. Helal, R. Hedhli, E. Ben Brahim, R. Jouini, A. Chadli *Habib Thameur Hospital, Tunisia Background & objectives: Bowen’s disease (BD) and actinic keratosis (AK) are squamoproliferative disorders of the skin. Histologically, they may mimic each other and they might be misinterpreted. p16 has been sug- gested to be a useful tool to make the differential diagnosis between them. Methods: We gathered 13 cases of BD and 9 cases of AK. The cases were stained for p16 using standard immunohistochemical techniques, and the staining patterns were categorised into one of five different patterns of the classification proposed by Harvey. Results: Mean age patients with BD and AK were 69 and 68 years respectively. All cases of BD and AK were positive to p16 with both nuclear and cytoplasmic staining. Intensity and extension of staining were different between BD and AK. For BD cases, the anti-p16 staining was pattern 1 for 12 cases (92%) and one case pattern 5. Concerning AK cases, staining was pattern 2 in 5 cases, pattern 3 in one case and pattern 5 in one case. Immunohistochem- istry was not contributive in one case. Conclusion: We have confirmed the previously published find- ings that immunohistochemistry for p16 in BD shows a consistent pattern of strong staining of all abnormal cells, presenting at least focal palisaded basal cell sparing. This pattern is not seen in AK. Where the staining is typically patches or scattered single cells of weak or moderate intensity. We believe that p16 can serve as a useful adjunctive test in supporting a diagnosis of BD in difficult cases and in separating it from AK. PS-12-016 Eccrine porocarcinoma: a clinicopathological study of 8 cases S. Ben Cheikh*, O. Belkacem, L. Belaid, S. Frini, A. Baccouche, A. Bdioui, L. Jaidane *Pathology Department, Sahloul University Hospital of Sousse, Tunisia Background & objectives: Eccrine porocarcinoma (EPC) is a rare malignant eccrine sweat gland tumour characterized by locally aggres- sive growth and high rates of extracutaneous metastasis. The aim of this study is to describe clinical and histopathological features of EPC. Methods: A retrospective review of medical records and histopa- thology slides of EPC cases between January 2000 and December 2022 was conducted using the cancer registry database of the cen- tre of Tunisia. Results: Eight EPC cases were included in this study. The mean age of diagnosis was 53.50 years (range 46-70 years) with seven females and one male. Systemic comorbidities were present in one patient. Clinically, EPC was described as ulcerated nodular lesion mimicking a squamous cell carcinoma in half of the cases. The most common localization was the scalp reported in 3 cases. Histo- pathological analysis revealed a tumour arising from the epidermis S133