Mucormycosis isolated from perilymphatic tissue: An unusual presentationB Chacko1, R Ananthakrishna1, Z Vasuki1, SD Thambu1, S Nair2
1 Department of Medicine, Christian Medical College, Vellore, India
2 Department of Pathology, Christian Medical College, Vellore, India
We present a rare case of a patient who presented with atypical cranial nerve palsies, with subsequent isolation of mucormycosis from an upper neck subcutaneous swelling. This is an unusual initial site of isolation of mucormycosis. We believe that this should be considered among the differentials when a diabetic or immunosupressed patient presents with cervical lymphadenopathy and cranial nerve palsies.
Keywords: Cervical swelling, facial cellulitis, fungal infection, mucormycosis
Mucormycosis is an aggressive, opportunistic infection caused by fungi in the class of phycomycetes, first described in 1885 by Paltauf. This typically originates in the nasal or oral mucosa, spreads to the paranasal sinuses and enters the orbit via the ethmoid and maxillary sinuses or via the nasolacrimal duct. It presents most frequently in immunocompromised patients, but can occur in healthy patients in the presence of often insignificant trauma. Diagnosis involves biopsy of affected sites-most commonly rhino cerebral, gastrointestinal and the lungs and molecular detection assays., In the following case, we report a very atypical site of isolation of mucormycosis from a subcutaneous swelling in the cervical region. We present this case report to suggest to clinicians that in a diabetic with cranial nerve palsies, even in the presence of normal sinuses and nasopharynx, mucormycosis needs to be considered as an important differential diagnosis and also how bacterial infections and subsequent antimicrobial therapy can increase the risk of developing this infection.
A 40-year-old man, a diabetic for four years came with a history of left-sided facial and neck swelling with pain a month prior to admission. This was followed two days later by left-sided facial weakness and decreased sensation over the same area and associated holocranial headache. There was no history of trauma, fever or features to suggest raised intracranial tension. He was treated by a local practitioner with a course of antibiotics following which the swelling decreased but the neurological deficits and headache persisted. He was then referred to our hospital for further evaluation.
On examination, he was found to have a small 1 x 1 cm soft non-tender subcutaneous nodule in the left upper deep cervical region. He did not have facial swelling or sinus tenderness.
Examination of central nervous system revealed evidence of fifth and seventh lower motor cranial nerve palsies; higher mental functions, fundus, motor, sensory and cerebellar examinations were normal. There was no evidence of meningeal irritation, proptosis or ophthalmoplegia. Rest of the systemic examination was normal.
At this point of time, the diagnosis considered was polyneuritis cranialis. The differential diagnosis considered included chronic meningitis due to tuberculosis or herpes zoster, metastasis due to nasopharyngeal carcinoma or lymphoma, demyelinating diseases, pachymeningitis and facial cellulitis with involvement of the peripheral components of the fifth and seventh nerves.
Investigations including cerebrospinal fluid cell counts, biochemical parameters, human immunodeficiency virus serology and cerebrospinal fluid cytology for malignant cells were negative. Blood sugar on admission was 300 mg/dl with no ketoacidosis.
Radiological evaluation revealed normal chest and paranasal sinuses. Magnetic resonance imaging of the brain and sinuses with gadolinium revealed a few non-specific small hyper-intense foci in the brain-the differentials offered were demyelination and vasculitis. Collagen disease work up, consisting of anti nuclear antibody, anti-neutrophil cytoplasmic antibodies, brainstem evoked potentials and magnetic resonance angiogram however were normal.
Nasopharyngolaryngoscopy and sinus biopsy were normal. The cervical swelling was then biopsied. Histopathology revealed broad filamentous hyphae that were aseptate and folded with variable width and stained positive with periodic acid schiff (PAS) and Gomorii methenamine silver stains adjacent to normal lymphoid tissue which was consistent with mucormycosis; culture however was negative.
This gentleman was started on amphotericin B at 1 mg/kg/day intravenously till a cumulative dose of 2.5 gm was reached. There was no further deterioration of neurological function and his headache improved significantly.
Mucormycosis being diagnosed from a cervical subcutaneous swelling is extremely rare. Usual sites of isolation are the nasopharynx, sinuses and infected soft tissues which usually have the more florid infection. The strange aspect of this case was the absence of the usual physical findings in a case of mucormycosis and the sole presence of a cervical swelling as the key to the diagnosis.
The points of discussion in this case are:
This patient appears to have developed left-sided facial swelling and pain which was initially treated with antibiotics-the swelling did subside, however his headache and the cranial nerve deficits worsened. There are case reports of physicians initially treating cellulitis in a diabetic as bacterial and when it worsens, do a biopsy of the tissue which reveals mucormycosis. It has been proposed that mixed bacterial infection establishes local and systemic conditions for the growth of mucormycosis. A mechanism for the progression of mucormycosis once the bacteria are killed may include the absence of bacteria (or bacterial products) or the absence of competition for nutrients like 'super infection'.
In this patient, the facial swelling and pain is most probably secondary to a bacterial infection (as it appears to have decreased to some extent with antibiotics) which as mentioned above supplies the milieu for growth of mucormycosis in a diabetic. Thus the fungal infection is most probably a secondary infection.
With our patient's cranial nerve involvement being restricted to the peripheral divisions of the fifth and seventh cranial nerves, it is logical to consider the above to be due to involvement following the superficial locally spreading infection and not due to direct intracranial invasion. The usual neurological involvement noted are ptosis, ophthalmoplegia and proptosis secondary to intracerebral extension which may occur via the orbital vessels or via the cribriform plate. Infranuclear facial nerve involvement has been rarely reported-in a case series it was observed in 22% cases whereas trigeminal nerve involvement has not been reported to date.
The diagnosis of mucormycosis can be made by direct microscopy or histopathological examination or by culture on Sabroud's agar. The detection of aseptate hyphae with right-angled branching is pathognomonic. Cultures are often negative and positive results alone are not sufficient to make the diagnosis as mucorales can be grown from specimens taken from uninfected mucosal and skin surfaces. All patients need to have tissue diagnosis either on smear and/or biopsy from affected tissues.
In summary we present a rare manifestation of mucormycosis and suggest that in patients with atypical lower motor neuron cranial nerve palsies with small cervical swellings, this rare infection should be thought of and evaluated for even in the presence of normal sinuses with no evidence of intracranial involvement.
We acknowledge the pathology department for the tissue diagnosis of mucormycosis.