PTL is more common in females than males, with a ratio of 1.6. This is remarkable, as other types of lymphomas are more prevalent in men [10]. The typical age upon diagnosis is between 50 and 80 years old, with the 7th and 8th decades being the highest. Rarely is PTL diagnosed in those under forty [11,12,13]. Similar to data from literature, in our study, the median age was 59.34 ± 13.6 years. As a known risk factor and possible precursor for PTL, Hashimoto’s thyroiditis could account for the higher age range and female preponderance of patients in comparison to other types of lymphoma [10, 14, 15]. In our cohort, the female-to-male ratio was 1.7.

The most common clinical presentation of PTL is progressive thyroid enlargement, sometimes in a brief period, with or without cervical lymphadenopathy, and compressive symptoms on the surrounding structures, such as vocal cord paresis, dysphagia, dyspnea, or dysphonia [16, 17]. In our cohort, only one patient presented with dyspnea and another one with dysphagia. Four patients were hypothyroid while eleven patients were euthyroid.

DLBCL is the most prevalent subtype of PTL, according to several earlier studies. Other common pathologies include follicular lymphoma and marginal zone, or MALT lymphoma [3, 18,19,20]. In our study, fifteen out of the included sixteen patients had DLBCL, while only one patient had MALT lymphoma. No cases of follicular or marginal zone lymphoma were recorded.

In terms of the diagnosis of PTL in our study, thyroid resection and open surgical biopsy were the most commonly used techniques. FNAB or core needle biopsy may offer a way to lessen the need for more invasive procedures and shorten the interval between clinical presentation and treatment when combined with flow cytometry, IHC, and fluorescence in situ hybridization (FISH) to check for gene rearrangement [4]. In our cohort, the majority of the included cases were diagnosed only after surgical intervention, while FNAB established the diagnosis only in three out of sixteen patients (18.75%). This agrees with the findings of the recently published multicenter study by Su M et al. [21]. All the included cases were positive for CD20, while markers such as CD10, BCL 2 & BCL 6 were expressed in 5,6, and 6 cases, respectively.

Nearly one-third of our patients (31.2%) were diagnosed as stage I, while the other two-thirds (68.8%) were diagnosed as stage II. In literature, stage I-IIE was the diagnosis for 88% of patients, according to Graff-Baker et al. [13]. Also, in a study by Chai et al., 92.1% of patients had a stage I–IIE diagnosis [14].

The management of PTL was based on many factors, including the histological type and the extent of the disease. The treatment consisted of chemotherapy, surgery, or a combination of both. Graff-Baker et al. discovered that 61% of patients in the Surveillance, Epidemiology, and End Results (SEER) database received surgical treatment, which is relatively high [13]. This is more than anticipated for a cancer where chemotherapy, with or without radiation, is the recommended course of treatment [13, 18, 22]. But it should be kept in mind that, on the contrary, surgical treatment alone is still advocated as a therapeutic option in stage IE tumors [23]. In our study, the most commonly used treatment modality was chemotherapy, with which fifteen patients were treated alone or in combination with diagnostic surgery. Four patients required second-line protocols due to the persistence of the disease despite initial treatment with first-line protocols.

PTL has had a good prognosis overall, with a high 5-year survival rate. Lack of treatment, advanced disease stage, follicular or diffuse large cell histological subtypes, and advanced age (over 80) are all linked to a worse prognosis [11, 12, 24]. Graff-Baker et al.‘s study included 1,408 patients from the SEER database and identified a median all-cause survival of 9.3 years and a 5-year overall survival of 66% [13]. A more recent analysis by Zhu Y et al. defined age, marital status, histological subtypes, stage, and treatment modalities as strong predictors of PTL-specific risk of death [25]. Regarding our results, remission was achieved in half of the patients after first-line chemotherapy, but no cures were reported after second-line treatments. At the end of the follow-up period, six patients were alive, four had died, and six were lost to follow-up. The median DFS was 35 months, and the OS was 37.5 months. This discrepancy of DFS & OS of the published studies can be attributed to three main factors: significantly shorter follow-up periods, the small sample size, and the discrepancies in the pathological variants.

It is acknowledged that this study has limitations. The most important one is the small number of patients. Additionally, it was only a single-center retrospective study, and we lost follow-up with some patients. Also, only nine out of sixteen patients underwent a PET-CT at the time of initial diagnosis. But it has strengths also; it presents a 16.5-year experience in a tertiary referral center of such a cohort. It also presents a rare form of thyroid malignancy that needs deeper understanding and research.