3.1.1 Diagnostic Considerations
In our case, the patient’s diagnosis of GSD was made based on a
combination of symptoms and imaging findings. Chronicity of his symptoms
over several years and absence of a primary tumor made a malignant
process highly unlikely. While osteolytic lesions do occur in the skull
base in Langerhans cell histiocytosis (LCH), LCH bone lesions more
commonly affect the calvarium and the temporal bone within the skull
base. CSF leaks may also occur with LCH but are more frequently
encountered in GSD. Furthermore, the presence of a mediastinal LM is
suggestive of CLA.
Historically, lymphangiomatosis was an umbrella “diagnosis” that
encompassed all CLA. The term, lymphangiomatosis, should be avoided
since it is non-specific and could delay appropriate care or
inadequately address potential complications. While our patient was
diagnosed with “lymphangiomatosis” early in life, the exact type of
CLA was not delineated because of diagnostic challenges. Sometimes the
initial clinical presentation does not offer all the clues for an
accurate diagnosis, especially in young children. Maintaining a high
index of suspicion and re-analyzing the diagnosis when new complications
occur is important.
Identification of the area of bone destruction and dura matter defect
can be difficult. The exact mechanism in which CSF leaks develop in GSD
is unclear but is hypothesized to occur when the lymphatic malformation
destroys the bone cortex of vertebrae or skull base and then infiltrates
into dura mater. Spinal instability secondary to significant vertebrae
or skull base destruction may also result in CSF leak.
Our patient’s case was complicated by recurrent meningitis infections, a
known complication of patients with GSD and skull base defects
[17-19]. Although the etiology of recurrent meningitis isn’t
completely understood, the highest risk of infection appears to be with
osteolytic nasotemporal lesions [17]. In our patient, oropharyngeal
bacteria presumably translocated from the sphenoid sinus through porous
eroded bone and into the CSF space through the dural mater defect. Our
patient was also asplenic, predisposing him to infection with
encapsulated bacteria. Comprehensive immunologic testing did not
identify a primary immunodeficiency.
Although our patient had thrombocytopenia, his platelet count normalized
after splenectomy, consistent with ITP. Furthermore, he had normal
fibrinogen levels and no hemorrhagic effusions, arguing against a
diagnosis of KLA.