Pilomatricoma with Focal Intralymphatic Extension Mimicking a Parotid Tail Neoplasm: A Diagnostic Challenge
Andries H. Groen 1, Kalpesh Hathi *1, Alexandra Eaton 2, Ryan DeCoste 2, Sean A. Rasmussen 2,
Timothy H. McCalmont 3,4, S. Mark Taylor 1
*Correspondence to: Kalpesh Hathi, Division of Otolaryngology-Head & Neck Surgery, Dalhousie University, Halifax, NS, Canada.
Copyright.
© 2026 Kalpesh Hathi, This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Received: 21 August 2026
Published: 01 September 2026
DOI: https://doi.org/10.5281/zenodo.22241300
Abstract
Introduction: Pilomatricoma is a rare benign adnexal neoplasm arising from hair matrix cells. Although the head and neck region represents the most common site of involvement, presentation in the parotid region is uncommon and frequently mimics salivary gland pathology. Preoperative diagnosis remains challenging because clinical examination, imaging, and fine needle aspiration are often nonspecific. Intralymphatic involvement in an otherwise benign pilomatricoma is exceptionally rare.
Case Presentation: A 24-year-old man presented with a progressively enlarging right infra-auricular mass. Fine needle aspiration cytology was inconclusive, while computed tomography (CT) demonstrated a lesion involving the tail of the parotid gland, radiologically suggestive of pleomorphic adenoma. Rapid progressive enlargement and overlying skin involvement prompted a right partial parotidectomy with skin excision, limited neck dissection, and reconstruction using a cervicofacial advancement flap. Histopathological examination demonstrated a 3.3 cm pilomatrical neoplasm with positive margins. External review by an expert dermatopathologist confirmed a pilomatricoma with focal minor intralymphatic extension and no evidence of pilomatrical carcinoma. Following multidisciplinary discussion, margin re-excision was performed and negative after re-resection.
Conclusion: Pilomatricoma should be considered in the differential diagnosis of superficial parotid tail masses. Cytology and radiological imaging may mimic salivary gland neoplasms. Focal intralymphatic extension may occur in otherwise benign lesions and should not automatically be interpreted as evidence of malignant transformation.
Keywords: Pilomatricoma; Pilomatrixoma; Parotid gland; Intralymphatic extension; Head and neck; Adnexal tumor.
Introduction
Pilomatricoma, previously referred to as calcifying epithelioma of Malherbe, is a benign adnexal tumour originating from hair matrix cells. It predominantly affects children and young adults and occurs most frequently in the head and neck region [1,2]. Despite its characteristic histopathologic appearance, preoperative diagnosis remains difficult and clinical diagnostic accuracy is poor [1,2].
Pilomatricomas are frequently misdiagnosed as epidermoid cysts, branchial anomalies, lymphadenopathy, and salivary gland neoplasms [1,2]. Lesions involving the preauricular and infra-auricular regions may pose a particular diagnostic challenge because imaging studies may suggest pathology arising from the parotid gland [3].
Histologically, pilomatricoma is characterized by a biphasic population of peripheral basaloid cells and central eosinophilic ghost cells, often associated with calcification and foreign-body giant-cell reaction [4,5]. Although malignant transformation into pilomatrical carcinoma has been described, pilomatricoma generally demonstrates indolent biological behaviour [4].
We present an unusual case of a pilomatricoma located adjacent to the tail of the parotid gland, clinically and radiologically mimicking a parotid neoplasm, with rapid progressive enlargement and demonstrating focal minor intralymphatic extension without features of malignancy.
Case Repesentation
A 24-year-old man presented to the otolaryngology clinic with a three-month history of a mass inferior to the right ear. Approximately one month before presentation, the lesion increased substantially in size, became erythematous and required incision and drainage in the emergency department. Thick material was evacuated, and a course of antibiotics resulted in partial regression. However, the lesion subsequently enlarged again.
His medical history included asthma, tympanostomy tube placement and wisdom tooth extraction. He was a nonsmoker and denied recreational drug use.
Physical examination revealed an approximately 2-cm mobile lesion located inferior to the right ear lobule and posterior to the angle of the mandible (Figure 1). Mild erythema of the overlying skin was present. The lesion was minimally tender and no additional cervical masses were identified. Facial nerve function was normal.
Fine needle aspiration cytology demonstrated aggregates of anucleate squamous cells associated with granulomatous giant-cell reaction. No malignant cells were identified. Cytologic findings were considered indeterminate and compatible with either a ruptured keratinous cyst or a squamous neoplasm.
Contrast-enhanced computed tomography demonstrated a well-defined enhancing lesion measuring 1.7 × 1.3 × 3.2 cm involving the tail of the right parotid gland and abutting the overlying skin. Imaging findings favoured a benign mixed tumour, with pleomorphic adenoma considered the leading diagnosis and Warthin tumour included in the differential diagnosis (Figure 2).
At subsequent review, progressive enlargement and increasing skin involvement were noted. Because of concern regarding cutaneous involvement and the presumed diagnosis of a benign parotid neoplasm, the patient underwent right partial parotidectomy, excision of involved skin, limited neck dissection, and reconstruction with a cervicofacial advancement flap.
Intraoperatively, the lesion measured approximately 4–5 cm and exhibited marked skin involvement. The tumour was readily separated from surrounding structures and there was no evidence of involvement of the facial nerve. Several superficial lymph nodes were removed.
Histopathological examination revealed a 3.3-cm well-circumscribed dermal-based neoplasm composed of a mixture of basaloid matrical cells and ghost/shadow cells with foci of keratinization and calcification (Figure 3). Tumour cells showed aberrant nuclear expression of B-catenin. These features were consistent with a pilomatricoma. However, several foci at the periphery of the tumour showed involvement of small vessels by tumour cells (confirmed with CD31 immunohistochemistry), raising the possibility of a malignant process. The tumour extended to the specimen margin. Because of unusual histologic findings, the specimen was referred for external consultation. Expert review confirmed a large nodular pilomatricoma with secondary granulomatous and anetodermatous changes and focal minor intralymphatic extension. Other features to suggest a pilomatrical carcinoma (infiltrative growth, necrosis, cytologic atypia, atypical mitoses) were not identified, and the final pathologic diagnosis was a pilomatricoma. 4 lymph nodes were negative for malignancy.
The case was subsequently reviewed at the multidisciplinary head and neck tumour board. In view of the positive margin and uncertain significance of the intralymphatic component, margin revision was recommended.
The patient subsequently underwent local re-excision under local anaesthesia with 5-mm margins extending to the deep cervical fascia and sternocleidomastoid muscle. Recovery was uneventful and facial nerve function remained normal and the margins were negative.
Discussion
Pilomatricoma is an uncommon benign adnexal neoplasm derived from primitive hair matrix cells and represents only a small fraction of cutaneous tumours [1,2]. Although the head and neck region account for approximately 60–80% of cases, involvement of the parotid region is distinctly uncommon [1,2]. Consequently, lesions in this location frequently raise suspicion for primary salivary gland pathology and may result in more extensive surgery than initially anticipated.
The present case illustrates the diagnostic difficulties associated with lesions arising adjacent to the tail of the parotid gland. Clinically, the lesion presented as an enlarging infra-auricular mass with overlying skin changes and recurrent inflammation. Radiologically, contrast-enhanced CT demonstrated a well-defined enhancing lesion involving the parotid tail, leading to a presumptive diagnosis of pleomorphic adenoma.
Similar observations have been reported by Koh et al., who described a giant pilomatricoma in the right parotid region in a pregnant woman [3]. In that case, imaging studies likewise suggested a lesion associated with the parotid gland. The intimate relationship between superficial adnexal tumours and the superficial lobe or tail of the parotid gland may render differentiation from salivary gland neoplasms difficult based on imaging alone. Consequently, pilomatricoma should be included in the differential diagnosis of superficial infra-auricular and preauricular masses, particularly in younger patients presenting with lesions associated with the overlying skin.
Fine needle aspiration cytology proved nondiagnostic in the present case. Cytologic examination demonstrated anucleate squamous cells accompanied by granulomatous giant-cell reaction, findings interpreted as indeterminate. Previous reports have highlighted the limitations of fine needle aspiration in pilomatricoma [1,2]. Depending on the relative proportions of basaloid cells, ghost cells, inflammatory cells and keratinaceous debris, cytologic specimens may be interpreted as epidermoid cysts, granulomatous inflammation, or even malignancy. The low preoperative diagnostic accuracy reported in the literature emphasizes the importance of maintaining a high index of suspicion when evaluating superficial lesions in the head and neck region [1].
Progressive enlargement and distortion of the overlying skin raised concern regarding possible malignancy in the present case. At the time of surgery, the lesion measured approximately 4–5 cm and required excision of the involved skin with reconstruction using a cervicofacial advancement flap. Although giant pilomatricomas have been described, most lesions are less than 3 cm in diameter [2]. Rapid enlargement and cutaneous changes have been reported in unusual variants and may result from secondary inflammation, rupture, foreign-body reaction and anetodermatous changes rather than malignant transformation [3,5].
The principal histopathologic differential diagnosis in the present case was pilomatrical carcinoma. Pilomatrical carcinoma is a rare malignant counterpart characterized by infiltrative growth, marked cytologic atypia, increased mitotic activity, necrosis, tissue destruction and frequent local recurrence [4,5]. None of these features were identified in our patient. Instead, external review by an expert dermatopathologist confirmed the lesion to represent a large nodular pilomatricoma with secondary granulomatous and anetodermatous changes.
This case highlights the importance of correlating unusual histologic findings with the overall architectural and cytologic features of the lesion rather than relying on isolated findings.
The most intriguing feature of this case was the presence of focal minor intralymphatic extension. To our knowledge, this finding has been only rarely documented in otherwise histologically benign pilomatricomas. Importantly, expert consultation specifically emphasized the complete absence of sufficient architectural and cytologic atypia to support a diagnosis of pilomatrical carcinoma.
The biological significance of intralymphatic involvement remains uncertain. In other benign neoplasms, intravascular or intralymphatic displacement of tumour cells has been described and does not necessarily imply metastatic potential. It is conceivable that previous inflammation, rupture and associated granulomatous reaction facilitated passive migration of tumour cells into lymphatic channels. In the absence of infiltrative growth, necrosis, cytologic atypia and increased mitotic activity, intralymphatic involvement alone should not be interpreted as evidence of malignancy. Nevertheless, because of the rarity of this finding and the presence of a positive margin, re-excision to achieve complete clearance was considered prudent.
Despite the clinically concerning appearance and unusual histologic findings, the lesion demonstrated benign biological behaviour. The patient retained normal facial nerve function and underwent successful margin revision under local anaesthesia.
The present case illustrates the importance of multidisciplinary management and expert pathological review in avoiding overtreatment. Although complete excision with negative margins remains appropriate management, isolated intralymphatic involvement should not automatically prompt radical surgery or be equated with pilomatrical carcinoma.
Conclusion
Pilomatricoma should be included in the differential diagnosis of superficial masses involving the parotid tail. Clinical examination, imaging studies and fine needle aspiration may be misleading, and definitive diagnosis ultimately relies upon histopathologic evaluation. Focal intralymphatic extension may occur in a pilomatricoma and should not automatically be interpreted as evidence of malignant transformation. Expert dermatopathology consultation and multidisciplinary management are essential to avoid overtreatment of these rare lesions.
Learing Points
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