“Lineage switch” is term described when leukemic cells on relapse exhibit a new phenotype, where losses of one lineage defining markers with simultaneous gain of another lineage defining markers occur. Relapse of acute leukemia is although a very common event, lineage switch occurs and reported very rarely in such cases. The pathogenesis involved in this phenomenon remains unclear; however plasticity of hematopoietic progenitor affected by intrinsic and extrinsic environmental cues can be a possible explanation. In most of the cases at the time of relapse conversion of B-acute lymphoblastic leukemia (ALL) to acute myeloid leukemia (AML) occurs. Here, we presented an unusual case of 10 year old boy with AML switched to T-ALL upon relapse, which is very rare and not well documented till date in literature. The diagnosis was further supported by morphologic, cytochemistry and flowcytometric immunophenotyping (FCM-IPT). Prognosis and survival of such cases remains poor even by the use of standard chemotherapy.

Basal cell carcinoma (BCC) constitutes the most common malignancy of the skin, accounting around 70% of all skin malignancies, especially in sun-exposed areas. The adenoid variant is a very uncommon subtype which accounts for approximately 1.3% of all BCCs. A 65-year-old male presented with ulcer and swelling on the left side of the nose and cheek with rolled borders for the past 2 years. Based on the histopathology and immunohistochemistry, the diagnosis of the adenoid type of BCC was made. One should be aware of its close mimics such as primary cutaneous adenoid cystic carcinoma before diagnosing adenoid BCC as they differ in prognosis and treatment modalities.

No abstract

e21525 Background: Synovial sarcoma (SS) is a relatively rare type of soft tissue sarcoma. Several prognostic factors have been described that modulate patients’ outcome. The aim of this study was to identify prognostic factors in patients with SS. Methods: A retrospective analysis was performed on clinical and histopathological data of patients treated at National Oncology Institute (Panama) between 1995 - 2007. Demographic, clinical, pathological, and therapeutic variables were reviewed. Overall survival and recurrence-free survival were analyzed using Kaplan-Meier and log-rank tests. Results: Twenty seven patients were analyzed, 56% male and 44% female, median age was 28. Tumour site; extremities based 85%, truncal 15%. Median tumour size was 8cm. Presentation; non-metastatic 84%, metastatic 16%. Histological type; monophasic 78%, biphasic 22%. Mitosis/10HPF; twenty and more 33%, less than twenty 67%. Necrosis; absent 63%, less than half 30%, and more than half 7%. Histological grade (FNCLLC); grade 2 48%, grade 3 52%. Surgery; limb sparing surgery 52%, amputation 48%. Treatment: adjuvant treatment 52% (3 chemotherapy only, 7 radiation therapy, 4 both). 90% were doxorubicin based regimens. The median follow up was 25 months. 63% of tumours recurred and 33% of patients died. Univariate analysis revealed a significant positive relationship between histological grade and overall survival (p<0.05). In patients with localized disease, time to recurrence decreased with histological grade (p=0.05 ns). Conclusions: High histological grade is an adverse prognostic factor for overall survival in patients with SS. No significant financial relationships to disclose.

Background–Papillary breast lesions constitute wide spectrum of heterogeneous pathological group. Diagnosis becomes challenging in case of overlapping histomorphological features. Material & methods–Retrospectively 69 papillary lesion were taken into consideration from January 2017 to March 2021.Results – Routine H&E & CK5/6, P63 is used for further differentiation. Cases were divided into three main divisions 1) benign –intraductal papilloma 2) atypical – intraductal papilloma with ADH/ DCIS 3) malignant - Intra ductal papillary carcinoma, encapsulated papillary carcinoma, solid papillary carcinoma & invasive papillary carcinoma. Papilloma comprised of 28 patients between 25-60 years of age & varies in size from 0.6 to 2.8 cm. Papilloma with ADH/DCIS accounted for 8 patients between 34-65 years age group with size of lesion between 0.5 to 3.0 cm. Intraductal papillary carcinoma comprised of 12 patients with size range 1.6 to 4.0 cm in age group of 42 to 65 years. Encapsulated papillary carcinoma comprised of 4 patients with age between 60 to 73 years and lesion size 0.8 to 14 cm. Solid Papillary carcinoma comprised of 10 patients between 39-81 years of age & lesion varies in size from 1.0 to 8.5 cm. Invasive papillary carcinoma comprised of 7 patients between age of 65 to 80 year and size varies between 2.0 to 6.5 cm. Conclusion – Diagnosis of papillary carcinoma is challenging and its classification includes different entities that have specific diagnostic criteria. Due to heterozygosity in morphology of benign, atypical and malignant subtypes, morphological features should be supplemented by IHC for accurate diagnosis.