Primary Malignant Melanoma of the Lacrimal Sac: A Case Report
Abstract
Background
Primary malignant melanoma of the lacrimal sac is a sporadic and aggressive tumor, accounting for less than 1% of all lacrimal sac neoplasms. Because its symptoms-such as persistent epiphora, medial canthal swelling or bloody discharge-closely resemble chronic dacryocystitis, diagnosis is often delayed until the disease has reached an advanced stage. Radiological imaging, particularly MRI and CT, plays a pivotal role in early detection, while definitive diagnosis relies on histopathology and immunohistochemistry. Recent advances in immunotherapy have expanded therapeutic options for mucosal melanomas in anatomically complex sites such as the lacrimal drainage system.
Case presentation
A 60-year-old man presented with progressive tearing and swelling at the left medial canthus, accompanied by intermittent blood-stained discharge for three months. Physical examination revealed a firm, non-mobile mass over the lacrimal sac without cutaneous ulceration. CT and MRI demonstrated a well-defined lesion within the left nasolacrimal canal, showing T1 hyperintensity and T2 hypointensity suggestive of a pigmented neoplasm. Histopathological examination confirmed malignant melanoma with immunopositivity for HMB-45, Melan-A and S-100. PET-CT revealed distant metastases at diagnosis. The patient received systemic immunotherapy with pembrolizumab (200 mg every three weeks), achieving partial remission before progression at 18 months. He was subsequently placed on palliative care.
Discussion
This case underscores the diagnostic challenges of lacrimal sac melanoma, given its rarity and nonspecific presentation. Multimodal imaging and early biopsy are crucial to distinguish it from chronic inflammatory disease. Immunotherapy, particularly PD-1 blockade, represents a promising alternative to extensive surgery in metastatic or unresectable cases.
Conclusion
Prompt recognition and multidisciplinary management are essential for improving outcomes in this aggressive malignancy. Lifelong surveillance remains mandatory due to the high risk of recurrence and metastasis.
Keywords: Lacrimal sac, Malignant melanoma; Mucosal melanoma; Immunotherapy; Pembrolizumab; Case report
Primary malignant melanoma originating from the lacrimal sac is exceedingly rare, with only a few dozen cases described in the medical literature1,2. Because its initial manifestations-such as persistent epiphora or medial canthal swelling-are nonspecific and often resemble chronic dacryocystitis, diagnosis is frequently delayed2,3. Advanced imaging modalities, including CT and MRI, are invaluable for evaluating the lesion’s extent and guiding management; typical features include T1 hyperintensity, T2 hypointensity and variable post-contrast enhancement, although signal characteristics may vary4,5. The definitive diagnosis depends on histopathological analysis supported by immunohistochemical markers such as HMB-45, Melan-A and S-1001,4. Given its aggressive nature and high recurrence potential, early identification and multidisciplinary treatment are critical2.
Case Presentation
A 60-year-old male
presented to the ENT Department with a three-month history of progressive
tearing and swelling in the left medial canthal region, accompanied by nasal
obstruction. The patient reported intermittent discomfort and occasional
blood-stained discharge from the left punctum. He had no history of trauma,
previous sinonasal surgery or cutaneous melanoma.
On clinical
examination, a firm, non-mobile mass measuring approximately 20 × 15 mm was
palpable over the left lacrimal sac, causing mild lower eyelid displacement.
The overlying skin appeared slightly discoloured but intact. Gentle pressure on
the sac produced no discharge. Ocular motility and visual acuity were preserved
(Figure 1).
Figure 1: Nasal endoscopy revealed a pigmented mass in
the region of the left middle meatus. CT dacryocystography demonstrated a
well-circumscribed soft-tissue lesion occupying the left nasolacrimal canal and
extending into the inferior meatus, measuring around 21 × 18 × 25 mm.
(Figure 2) the lesion appeared spontaneously hyperdense,
with smooth bony remodelling but no destruction
Figure 2: Lesion occupying the left nasolacrimal canal
and extending to the inferior meatus
MRI revealed an ovoid
lesion at the left medial canthus that was hyperintense on T1-weighted images,
hypointense on T2 and showed heterogeneous enhancement after contrast
administration (Figure 3). These features favoured a neoplastic process
over inflammatory dacryocystitis3-5.
Figure 3: Lesion at the left medial canthus that was
hyperintense on T1-weighted images
Histopathological
examination of a biopsy specimen revealed sheets of epithelioid and spindle
cells containing melanin pigment. Immunohistochemistry confirmed melanocytic
differentiation, positive for HMB-45, Melan-A and S-1001,4.
Staging PET-CT
demonstrated distant metastases. The patient received immunotherapy with
pembrolizumab. Follow-up CT revealed new metastatic lesions (Figure 4)
and the patient was transitioned to palliative care approximately 18 months
after presentation. He was subsequently lost to follow-up.
Figure 4: Metastatic lesions
Discussion
Primary malignant
melanoma of the lacrimal sac accounts for less than 1% of tumours in this area
and poses a significant diagnostic challenge2.
It generally affects individuals in their sixties or seventies, with a slight
female predominance1,2. Due to
the similarity of symptoms to benign conditions, numerous patients receive
inappropriate treatment for suspected chronic dacryocystitis prior to the
accurate diagnosis being made2,3.
The histogenesis of
melanoma in the lacrimal sac is still not fully understood. While melanocytes
are typically absent from the lacrimal drainage system, their presence may be
attributed to abnormal migration of neural crest-derived cells during embryonic
development or secondary migration from the conjunctiva6,7. This phenomenon accounts for the
emergence of primary melanocytic neoplasms in this otherwise atypical location.
Radiological imaging is
crucial in distinguishing melanoma from other lesions. CT scans frequently
display a well-defined soft-tissue mass within the lacrimal sac or nasolacrimal
duct, usually accompanied by smooth bony expansion rather than erosion3,5,7. MRI results can vary based on melanin
levels and the presence of haemorrhage, but lesions often exhibit T1
hyperintensity and T2 hypo intensity4,5.
Although these characteristics are not definitive, they may indicate a
pigmented neoplasm and lead to an early biopsy.
Histopathological
examination is vital for diagnosis confirmation. The tumour is characterized by
nests or sheets of epithelioid or spindle-shaped cells that contain coarse
melanin granules. Immunohistochemical positivity for HMB-45, Melan-A and S-100
reinforces the diagnosis and aids in ruling out poorly differentiated
carcinomas or sarcomas1,4.
Due to the rarity of
cases, there is no established treatment protocol. Traditionally, wide surgical
excision-often involving dacryocystectomy and partial medial maxillectomy-has
been the main treatment strategy, with adjuvant radiotherapy for close or
positive margins2,3,7,8.
Nevertheless, recurrence rates surpass 50% within two years and the prognosis
remains uncertain2. Recent
advancements in treatment options are being explored9,10.
Conclusions
Primary malignant
melanoma of the lacrimal sac is an uncommon and highly aggressive neoplasm that
often presents with nonspecific symptoms, leading to delayed diagnosis.
Comprehensive imaging, prompt histopathologic evaluation and coordinated
multidisciplinary care are vital for optimizing outcomes. Although surgical
excision remains the traditional mainstay of therapy, immunotherapy represents
a promising organ-preserving alternative, particularly in unresectable or
metastatic cases. The favourable outcome observed in this case supports the
expanding role of immune checkpoint inhibitors in managing rare mucosal
melanomas. Lifelong follow-up remains crucial to monitor for recurrence or
distant metastasis.
References
8. Lloyd WC, Leone CR.
Malignant melanoma of the lacrimal sac. Arch Ophthalmol 1984;102:104-107.