Malignant lymphoma arising in the middle ear and mastoid cavity is exceedingly rare [1-3], and its initial manifestations often resemble chronic infectious or inflammatory otologic disease, leading to significant diagnostic delay [4-6]. Although most lymphomas originate in lymph nodes and lymphoid tissue, approximately 25%-30% of non-Hodgkin lymphomas present at extranodal sites. Within the head and neck, the Waldeyer’s ring, oral cavity, sinonasal tract, nasopharynx, and skin are the most frequently involved regions, whereas primary disease of the temporal bone is exceptional, particularly of T-cell lineage which poses greater diagnostic and therapeutic challenges due to its aggressive nature [1,2]. Because otorrhea, hearing disturbance, otalgia, and facial paralysis are common in complicated otitis media or mastoiditis, and because early radiologic imaging may show only nonspecific soft-tissue opacification or fluid within the middle ear and mastoid, otologic lymphomas are easily misattributed to infection [4,5,7]. Herein, we describe a rare case of a 56-year-old male who presented with right-sided hearing loss and facial paralysis. While initially diagnosed with chronic mastoiditis, radiologic evaluation, histopathologic examination, and immunohistochemical analysis ultimately confirmed the diagnosis of peripheral T-cell lymphoma (PTCL).

A 56-year-old male presented with right-sided hearing loss and tinnitus that had initially developed 4 months prior. While these symptoms showed a transient and partial improvement following a course of oral antibiotics prescribed at a local clinic, they significantly exacerbated over the past 2 weeks. During this recent period of worsening, the patient also experienced persistent otorrhea and non-vertiginous dizziness, although no spontaneous or provoked nystagmus was observed during the bedside vestibular examination.

One year earlier, the patient was evaluated for diffuse leukoplakia with mucosal hardness on the right dorsal tongue (Fig. 1). An excision biopsy revealed a dense infiltration of small-sized lymphoid cells with epidermotropic lymphocytes. Immunohistochemistry staining was positive for CD3 and CD5, with a predominance of CD4+ cells over CD8+ cells. The Ki-67 proliferation index was measured at 60%-70%. Crucially, a T-cell receptor (TCR) gamma gene rearrangement study using PCR-fragment analysis confirmed T-cell monoclonality. Correlating these findings with the clinical context of gastrointestinal involvement, the lesion was diagnosed as an oral manifestation of iTLPD-GI. Because iTLPDGI typically follows a non-aggressive clinical course and rarely responds to conventional cytotoxic therapies, a “wait-and-watch” strategy was adopted by the hemato-oncology department. The patient remained completely asymptomatic, and the tongue lesion showed no localized progression or morphological changes during this observational period, warranting no initial systemic chemotherapy or local radiation.

Physical examination revealed tenderness upon palpation of the right postauricular area, accompanied by swelling and erythematous changes of the overlying skin. Marked edema of the external auditory canal (EAC) precluded endoscopic visualization of the right tympanic membrane. While an initial superficial EAC biopsy was performed, it yielded nondiagnostic results, showing only non-specific inflammatory cells. Preoperative bacterial cultures were also uninformative. Pure-tone audiometry revealed profound hearing loss in the right ear with no measurable air or bone conduction thresholds (scale-out), whereas the left ear showed normal thresholds (air 18 dB HL; bone 18 dB HL). On return for reassessment after the audiometric evaluation, the patient had developed right facial weakness consistent with House-Brackmann grade IV.

Temporal bone computed tomography revealed homogeneous soft-tissue attenuation opacifying the right middle ear and mastoid cavity with erosive changes involving the epitympanic roof and ossicles. Notably, temporal bone CT revealed dehiscence of the facial nerve canal at the first genu, accompanied by suspected nerve edema extending along the labyrinthine and tympanic segments (Fig. 2). Due to worsening headache, brain magnetic resonance imaging (MRI) was performed, revealing diffuse pachymeningeal enhancement and peridural edema in the right temporal bone, suggesting an infiltrative process rather than simple mastoiditis (Fig. 3). Positron emission tomography-CT (PET-CT) was subsequently conducted. The PET-CT demonstrated increased uptake in the right mastoid region and periauricular soft tissue (Fig. 4).

Although malignancy was strongly suspected based on the imaging and prior history, a definitive tissue diagnosis had not yet been established. Given the refractory nature of the symptoms, the development of cranial neuropathy, and the dural involvement on MRI, a radical mastoidectomy was performed. The primary goals of the surgery were to secure a definitive deep-tissue diagnosis, to achieve therapeutic decompression of the facial nerve and dura, and to perform tumor debulking to reduce the local burden.

Intraoperatively, the right middle ear and mastoid cavity were completely occupied by tumor tissue (Fig. 5A), resulting in exposure of the facial nerve and erosion of the ossicles. The mass further extended to the middle cranial fossa, exposing the dura and adjacent cortex (Fig. 5B). Because the dura was thickened and compromised, duraplasty was performed using an abdominal fat graft (Fig. 5C).

Permanent histopathology demonstrated a diffuse infiltrate of pleomorphic atypical lymphoid cells with irregular nuclear contours on hematoxylin-eosin stain (Fig. 6). Immunohistochemical profiles confirmed a T-cell lineage, with positive expressions of CD3, CD5, CD4 (most cells), and CD8 (some cells), while CD20 highlighted background B-cells. Notably, the Ki-67 proliferation index was high at 60%-70%, and Granzyme B showed focal positivity, suggesting an aggressive nature.

These findings, in conjunction with the previous oral specimen, were highly suggestive of a disease progression from the antecedent indolent T-cell lymphoproliferative lesion. Although a formal PCR-based TCR gamma gene rearrangement study was restricted to the initial tongue lesion and not extended to the dural specimen, the temporal bone lesion exhibited an immunophenotypic profile (CD3+, CD5+, and CD4+ dominance) completely identical to that of the prior tongue lesion. An outside consultation with a specialized hematopathologist further confirmed the diagnosis as PTCL. Consequently, based on the identical pan-T-cell marker expressions and the distinct clinical timeline, the case was established as an aggressive clonal transformation of iTLPD-GI into PTCL involving the temporal bone.

Following the diagnosis, the patient was referred to the hemato-oncology department and underwent a comprehensive workup. The patient completed four cycles of CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone) combined with intravenous methotrexate (MTX). Subsequent management included three cycles of high-dose MTX but the response was evaluated as stable disease with a suboptimal clinical response. To achieve better local control, whole-brain reasonably justifying initial empiric antibiotic therapy. However, failure to respond to appropriate antibiotics—particularly when accompanied by cranial neuropathy, escalating pain, headache, or progressive canal obstruction—should lower the threshold for advanced imaging and tissue diagnosis [2,5,7].

In the temporal bone, contrast-enhanced MRI is particularly informative because marrow and dural interfaces are more distinctly visualized than on CT. Pachymeningeal enhancement adjacent to diseased bone, as seen in this case, is atypical for middle ear infection or mastoiditis and should raise suspicion for an infiltrative or malignant process [3,8]. PET-CT, while not specific, can complement MRI by demonstrating regional hypermetabolism and evaluating for multifocal or systemic disease [6,7].

Radiologically, middle ear and mastoid lymphomas often present as homogeneous soft-tissue opacification with variable bone erosion [1,3,5]. These findings overlap substantially with chronic otomastoiditis or cholesteatoma, particularly when sclerosis or coalescent changes are present. Features that favor lymphoma include relatively uniform soft-tissue density without the typical retraction pocket or keratin debris seen in cholesteatoma, but with associated facial nerve involvement and dural thickening or enhancement. Nevertheless, imaging alone cannot reliably distinguish lymphoma from infection or other neoplasms, making tissue diagnosis indispensable.

Regarding the surgical management, the decision to proceed directly to radical mastoidectomy as the initial intervention warrants explicit justification, as chemotherapy is the primary treatment for systemic T-cell lymphoma. In this case, the rationale was twofold. First, because the initial superficial EAC biopsy was non-diagnostic, a definitive histopathological diagnosis via deep-tissue acquisition was mandatory before initiating aggressive systemic chemotherapy. Second, and more importantly, the patient’s clinical presentation including HB grade IV facial palsy and radiologic evidence of dural compromise, mandated immediate surgical intervention. Even in the context of complicated chronic otitis media, such neurological and intracranial findings are absolute indications for emergent surgical exploration and decompression. Therefore, surgery served as an essential emergency intervention to prevent further neurological deterioration and potential intracranial complications, such as meningitis, while simultaneously providing the necessary tissue for diagnosis and achieving local tumor debulking.

From a pathobiologic standpoint, T-cell lymphomas constitute a minority of non-Hodgkin lymphomas and generally carry a less favorable prognosis compared with most B-cell counterparts [1,2,9]. Extranodal T-cell disease confined to, or prominently involving, the temporal bone is exceptional, with the literature consisting largely of isolated case reports and small series [1-3].

In such clinical scenarios, a history of prior or coexisting T-cell lymphoproliferative disease is crucial. iTLPD-GI is a rare, mature T-cell lymphoproliferative disorder characterized by a clonal but non-destructive infiltration of small, mature T-cells throughout the gastrointestinal tract. While it typically follows a protracted, indolent clinical course, our case illustrates a significant clinical caveat. The initial tongue biopsy had already confirmed T-cell monoclonality via TCR gamma gene rearrangement and a high Ki-67 index (60%-70%), with a pathological warning regarding potential higher-grade progression. The temporal bone lesion exhibited an immunophenotypic profile completely identical to that of the antecedent oral lesion, characterized by a shared dominance of CD3+, CD5+, and CD4+ expressions. In peripheral T-cell malignancies, the sharing of identical pan-T-cell markers at metachronous extranodal sites serves as a highly reliable surrogate indicator for clonal continuity. As demonstrated here, the subsequent development of PTCL in the temporal bone highlights the potential risk of aggressive clonal transformation of iTLPD-GI at extranodal sites [2,5].

Similar cases have reported that T-cell lymphoma involving the temporal bone may initially be misdiagnosed as chronic otitis media or mastoiditis [1,2,6]. For instance, Ho, et al. [1] described a 1-year-old boy who presented with otorrhea, otalgia, and acute mastoiditis complicated by facial palsy, was initially treated with intravenous antibiotics, but was ultimately diagnosed with high-grade PTCL following mastoid exploration and biopsy. Likewise, Jumaat, et al. [6] reported a case in which lymphoma involving the middle ear and temporal bone was initially presumed to be an infectious process, leading to a delay in appropriate treatment.

As summarized in Table 1, a focused review of temporal bone lymphomas highlights distinct clinicopathologic features and prognostic divergences between lineages. Early-onset facial nerve palsy serves as a consistent clinical “red flag” across all reported cases of temporal bone lymphoma, including T-cell lineage (Ho, et al. [1], Li, et al. [2], Danino, et al. [10], and the present case) and B-cell lineage (Jumaat, et al. [6], Kanzaki, et al. [11]). Notably, this acute neurological deterioration occurs even in the absence of extensive bony destruction, distinguishing it sharply from advanced cholesteatoma.

Interestingly, while most reported cases are primary presentations, our patient is the first documented case to arise in the context of iTLPD-GI, suggesting a specific biological pathway of clonal evolution. Furthermore, our case demonstrated dural involvement and severe headache, which are relatively rare but critical indicators of intracranial extension that necessitate urgent surgical intervention for decompression and duraplasty. The clinical course further underscores the aggressive nature of this malignancy; the patient achieved initial complete remission (CR) of the primary lesion following CHOP combined with IV MTX and radiotherapy, but suffered a systemic relapse in the stomach and pancreas 18 months later.

This case illustrates that lymphoma involving the middle ear and temporal bone can be difficult to distinguish from chronic infectious diseases in the early clinical course. Therefore, in patients with chronic otitis media or mastoiditis who show poor response to treatment or present with atypical clinical features such as cranial neuropathy or dural enhancement, surgery should be considered not only for staging but as an immediate intervention to manage complications and secure a definitive diagnosis [5,6,9].